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TRH03XM COOK BOOK
www.3ALogics.com |
COOKBOOK |
Scope This document contains information such as example circuit, guide, etc to help users to develop
HF (13.56MHz) RFID reader system more easily and conveniently.
(Reference system: 3ALogics Evaluation board – RSK100, RSK200L, RSK300)
Related 3ALogics Products TRH031M
TRH033M
Cookbook construction This Cookbook is divided by applications and provides actual test cases and examples with
theoretical explanations.
Application Access Control / Home Network & Digital Door Lock
POS Terminal / Public Transportation
Electronic Library / Intelligent Toys
E-Parking / Product Authentication
Distribution, Logistics
Confidential 1
TRH03XM COOK BOOK
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Revision history
Date Version Content
2008. 04. 11 0.1 Preliminary release
2008. 04. 16 1.0 1.0 version release
Notice : All referenced brands, product names, service name and trademarks are the property
of their respective owners.
AnyRead™ - is a trademark of 3ALogics.
Copyright © 2008 3ALogics Inc.
This draft document is a copyright-protected by 3ALogics. Except as permitted under the
applicable laws of the user’s country, neither this draft document nor any extract from it may
be reproduced, stored in a retrieval system or transmitted in any form or by any means,
electronic, photocopying, recording or otherwise, without prior written permission.
Disclaimer
3ALogics accepts no liability for the content
of this document, or for the consequences of
any actions taken on the basis of the
information provided, unless that information is
subsequently confirmed in writing. If you are
not the intended recipient you are notified that
disclosing, copying, distributing or taking any
action in reliance on the contents of this
information is strictly prohibited.
Contact 3ALogics Inc.
7th Fl., Hyundai-office Bldg., 9-4, Sunae-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-783 Korea TEL : (82)-(31)-715-7117 FAX : (82)-(31)-719-7551
Homepage: http://www.3ALogics.com
E-mail : [email protected]
Printed in the Republic of Korea.
TRH03XM COOK BOOK
www.3ALogics.com | Confidential 3
Document Contents
Chapter1 Concept of RFID and Reader IC Usage _________________________________ 7
1.1 RFID (Radio Frequency Identification) Concept ________________________________________________ 7
1.2 Reader IC (TRH03XM) Usage and Functions ___________________________________________________ 8
1) Usage __________________________________________________________________________________________ 8
2) Functions ______________________________________________________________________________________ 8
Chapter2 Reader System Configuration Using Atmel AT89C51ED2 _______________________________ 9
2.1 TRH03XM Interface _____________________________________________________________________________ 9
2.2 Clock Oscillator Related Circuit _________________________________________________________________ 9
2.3 TRH03XM and Microprocessor Interface ______________________________________________________ 10
1) Selecting Microprocessor Interface __________________________________________________________ 10
2) H/W Configuration by Interface Type ________________________________________________________ 11
3) H/W Configuration for SPI mode ____________________________________________________________ 12
2.4 Use Case of Atmel AT89C51ED2 ______________________________________________________________ 13
Chapter3 Designing HF Reader Antenna _______________________________________ 16
3.1 HF RFID System _______________________________________________________________________________ 16
3.2 Inductive Coupling RFID System Design Parameter ___________________________________________ 17
1) Magnetic field strength: H (A/m) ____________________________________________________________ 17
2) Couple Coefficient: k _________________________________________________________________________ 17
3) Resonance ____________________________________________________________________________________ 18
3.3 Antenna Design _______________________________________________________________________________ 18
3.4 Designed Antenna Radiation Pattern _________________________________________________________ 19
TRH03XM COOK BOOK
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Chapter4 Antenna Matching Optimization and Application ___________________ 20
4.1 TRH03XM Antenna Matching Scope __________________________________________________________ 20
4.2 EMC Filter Impedance _________________________________________________________________________ 22
4.3 Directly Antenna Matching Method ___________________________________________________________ 23
1) Antenna Coil impedance measurement ______________________________________________________ 23
2) Antenna matching____________________________________________________________________________ 23
3) Antenna matching results ____________________________________________________________________ 24
4.4 EMC filter and matched antenna ______________________________________________________________ 25
4.5 Receiver Configuration ________________________________________________________________________ 26
4.6 Antenna and Q factor _________________________________________________________________________ 27
Chapter5 How to Design 50Ω Matching Circuit using Balun _______________________________ 28
5.1 Scope __________________________________________________________________________________________ 28
5.2 Balun and Antenna Circuit ____________________________________________________________________ 29
1) Balun Related Circuit _________________________________________________________________________ 29
2) Antenna Configuration _______________________________________________________________________ 30
5.3 Matching Process ______________________________________________________________________________ 30
5.4 Measurement __________________________________________________________________________________ 31
5.5 Gerber _________________________________________________________________________________________ 32
Chapter6 How to use TX Power Boost Up ______________________________________ 33
6.1 Power Boost Up _______________________________________________________________________________ 33
6.2 MOS Model Power Booster Design ___________________________________________________________ 34
1) MOS Model __________________________________________________________________________________ 34
2) DC Bias Circuit _______________________________________________________________________________ 35
3) Stability _______________________________________________________________________________________ 37
4) Input and Output Matching and Measurement _____________________________________________ 41
6.3 Power Booster Design Using S2P File _________________________________________________________ 44
1) S2P File Extract _______________________________________________________________________________ 44
2) Input/Output Matching and Measurement __________________________________________________ 45
TRH03XM COOK BOOK
www.3ALogics.com | Confidential 5
Chapter7 EMC Problem Solving _________________________________________________ 47
7.1 EMC (Electromagnetic Compatibility) Scope __________________________________________________ 47
7.2 Electromagnetic Waves Radiation Standard ___________________________________________________ 48
7.3 EMI Noise Measure ____________________________________________________________________________ 48
1) Noise Measure Basis _________________________________________________________________________ 48
2) Noise Measure Technology __________________________________________________________________ 48
7.4 Reader System Design with EMI Noise Consideration ________________________________________ 49
1) System Noise Origination with TRH03XM ___________________________________________________ 49
2) Component Selection and Filtering __________________________________________________________ 49
3) Layout and Routing __________________________________________________________________________ 50
4) Shielding _____________________________________________________________________________________ 51
5) Other Considerations ________________________________________________________________________ 53
Chapter8 Air interface Measurement ___________________________________________ 54
8.1 Air interface ___________________________________________________________________________________ 54
8.2 Measurement __________________________________________________________________________________ 54
8.3 100% ASK Waveform __________________________________________________________________________ 55
1) ISO/IEC 14443A ______________________________________________________________________________ 55
2) ISO/IEC 15693 ________________________________________________________________________________ 56
8.4 10~30% ASK Waveform _______________________________________________________________________ 57
1) ISO/IEC 14443B ______________________________________________________________________________ 57
2) ISO/IEC 15693 ________________________________________________________________________________ 58
Chapter9 Modulation Index Control ____________________________________________ 59
9.1 Modulator Concept____________________________________________________________________________ 59
9.2 Modulator Index Adjustment __________________________________________________________________ 60
1) Standard Modulation Index __________________________________________________________________ 60
2) Modulation Index Control ____________________________________________________________________ 61
9.3 Adjustment Guide _____________________________________________________________________________ 63
TRH03XM COOK BOOK
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Chapter10 Understanding Demodulation Actions ______________________________ 65
10.1 What is Demodulation? ______________________________________________________________________ 65
10.2 Demodulation Register _______________________________________________________________________ 66
10.3 Demodulation Signal Measurement _________________________________________________________ 68
1) Measurement Set up _________________________________________________________________________ 68
2) Measurement _________________________________________________________________________________ 69
Chapter11 Using Card detector _________________________________________________ 72
11.1 Card Detector Principle ______________________________________________________________________ 72
11.2 Card Detector Application ___________________________________________________________________ 72
11.3 Card Detector Movement ____________________________________________________________________ 73
1) Card Detector Basic Movement ______________________________________________________________ 73
2) Card Detector Register Map _________________________________________________________________ 73
11.4 Card Detector Set-up Procedure _____________________________________________________________ 74
11.5 Practical Application _________________________________________________________________________ 75
TRH03XM COOK BOOK
www.3ALogics.com |
Chapter1 Concept of RFID and Reader IC
Usage
1.1 RFID (Radio Frequency Identification) Concept
RFID is an automatic identification technology using air interface to retrieve data from tags.
Concept of reading tag information is similar to reading barcode. However, reader does not
need to be so close to the tag to read data. Some tags can be read from several meters away
and beyond the line of sight of the reader. Also multiple tags can be read simultaneously so
application area is very broad.
RFID system comprise of reader, antenna, tag, server and network. As seen on below Picture
1-1, PC sends command to reader to read signal, then through antenna, tag signal is transmitted
to reader. This data is converted to recognizable form and sent to PC.
Below Picture 1-1 displays RFID system implementation.
ModulationMagnetic field
TransmitterControl
&Analysis
Confidential 7
Receiver
TAGIC
Demodulation
Picture 1-1 RFID System Implementation
TRH03XM COOK BOOK
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1.2 Reader IC (TRH03XM) Usage and Functions
1) Usage
13.56MHz RFID reader system is left block of Picture 1-1. Microprocessor is a controller for
analysis function. 3ALogics reader IC will perform the roll transmitter and receiver. Reader IC
receives command and data from microprocessor and converts signal to meet each protocol
specifications. This signal is transferred to tag through antenna. Receiving process is in reverse
of previous process. Received data is converted to digital data by Reader IC and stored in FIFO.
Afterwards, microprocessor takes data received through reader IC. Basically microprocessor
communicates with tag through reader IC, thus, reader IC provides air interface communication
capability.
2) Functions
- Modulation / Demodulation
- Encoding / Decoding
- Framing
- Data integrity
- Timer and interrupt
(Refer to: TRH031M Data sheet)
TRH03XM COOK BOOK
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Chapter2 Reader System Configuration Using Atmel
AT89C51ED2
2.1 TRH03XM Interface
TRH03XM do not embed microprocessor thus TRH03XM must be controlled by separate
microprocessor. Therefore, user must configure interface with microprocessor to function
TRH03XM. This chapter explains interface between microprocessor and TRH03XM (except RF
interface) and related circuit configurations.
2.2 Clock Oscillator Related Circuit
Very basic circuit to function TRH03XM is Clock Oscillator. Circuit using Crystal Oscillator to
operate TRH03XM is described in below picture. This circuit, unlike ordinary circuits, connected
with 1MΩ resistor in parallel with Crystal Oscillator.
Picture 2-1 Clock Oscillator Related Circuit
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TRH03XM COOK BOOK
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2.3 TRH03XM and Microprocessor Interface
1) Selecting Microprocessor Interface
TRH03XM supports 5 types of microprocessor interface. Therefore, user must select what
interface will be used prior to configuring TRH03XM hardware. First thing to be considered in
selecting interface is availability of ports quantity for microprocessor and TRH03XM interface.
Chart 2-1 Number of Ports by Interface
Interface Type Number of Ports Parallel/Serial
SPI 5 Serial
Separated Multiplexed 13 Parallel
Common Multiplexed 13 Parallel
Separated Dedicated 15 Parallel
Common Dedicated 15 Parallel
Next is communication speed. SPI mode is slower than other available interfaces.
Each interface has both advantages and disadvantages. However, 3ALogics recommends
Separated Multiplexed mode if enough ports are available, and SPI is recommended if minimum
quantity of ports is needed.
TRH03XM COOK BOOK
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2) H/W Configuration by Interface Type
After selecting interface type next step is to configure hardware to fit that type. Whether to
select Separated mode or Common mode is determined by software thus user only need to
configure hardware if using Multiplexed mode and Dedicated mode. Also hardware can be
configured to select Multiplexed mode and Dedicated mode by software.
Picture 2-2 displays hardware configuration method by interface type. For Multiplexed mode,
ADDR2, ADDR1, and ADDR0 are assigned High, High, and Low value. However, this is just an
example and user can select each value. However, using Dedicated mode, PALE value must have
High value.
Picture 2-2 Hardware Configuration Method by Interface Mode
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TRH03XM COOK BOOK
3) H/W Configuration for SPI mode
Picture 2-3 displays hardware configuration using SPI mode. When SPI is embedded in
microprocessor connect circuits corresponding to each port name (NSS, MOSI, SCK, and MISO).
If SPI is not embedded in microprocessor then select arbitrary port to connect NSS, MOSI, SCK,
and MISO and operate using software. From the picture each High/Low value assigned to each
port cannot be changed by user. TRH03XM SPI communication will not function if wrong
High/Low value is entered.
Picture 2-3 H/W Configuration Method Using SPI Mode
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TRH03XM COOK BOOK
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2.4 Use Case of Atmel AT89C51ED2
Based on information provided in previous chapter, here is a use case using 3ALogics RSK
board. (Reference: RSK100, RSK200L, and RSK300)
(a) Schematic
Dedicated/Multiplexed
Address mode
Confidential 13
RDB
PALE
CSB
WRB
DATA0~7
ADDR0~2
RSTP0.7/AD7
P0.6/AD6
P0.5/AD5
P0.4/AD4
P0.3/AD3
P0.2~0/AD2~0
P1.0~P1.7
(b) Interface Configuration
Picture 2-4 AT89C51ED2 Related Circuit Configuration (RSK board)
TRH03XM COOK BOOK
Atmel’s AT89C51ED2 is used for μ-Processor. TRH03XM chip and MCU interface are configured
to select Multiplexed mode and Dedicated mode using software (Picture 2-4). Total of 4 ports (8
bit port: P0, P1, P2, P3); P0 controls TRH03XM, P1 is TRH03XM data port, P2 controls LCD, and P3
is allocated for interrupt and RS232 communication port. AT89C51ED2 has 64K byte flash ROM
and 256byte RAM so programming is possible. For programming mode selection, PSEN is the
circuit to handle process. POR (Power On Reset) circuit for chip initial reset, Crystal Oscillator for
system clock, and RS232 circuit for RS232 communication. Circuits for LCD control and
configuration are for RSK board application only. They are optional circuits for hardware
configuration and not required for other RFID application development.
Picture 2-5 TRH03XM Related Circuit Configuration (RSK board)
TRH03XM is configured to 3 power source (AVDD, DVDD, and TVDD) for reliable supply of
power and to avoid Analog/Digital electric noise interference. AVDD is Receiver power. DVDD is
Digital power, and TVDD is Transmitter power. Circuit should be designed separating power as
seen on Picture 2-5.
However for ground, since substrate is not separated from chip internally, should be designed
to share AVSS, DVSS, and TVSS externally.
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At this point basic circuits are configured to control TRH03XM, and Analog part remains that is
TRH03XM COOK BOOK
www.3ALogics.com | Confidential 15
key feature of RF Transceiver. Transmitter comprises of EMC filter layer (Converts square wave to
Analog sine wave), matching layer configured between Antenna and filter layer, and Antenna.
Receiver comprises of attenuator resistor (to send high voltage signal from antenna to chip
inner part) and circuit for DC offset re-modulation. Detailed information is available in Chapter 3
and 4.
TRH03XM COOK BOOK
Chapter3 Designing HF Reader Antenna
3.1 HF RFID System
RFID systems work largely based on inductive coupling theory. Therefore, to understand
electric power and data communication, user should understand magnetic field and electric
theory. Less than 30MHz RFID applications, inductive coupling is used for data transmitting and
receiving. For above 30MHz, data transmitting and receiving are based on electromagnetic
waves. Antenna design method, power calculation and theory are similar to standard RF
communication. It’s easy to get confused with HF Antenna and power calculation. Picture 3-1
displays inductive coupling scope diagram. It performs like transformer in electronic circuit.
Picture 3-1 Inductive Coupling
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3.2 Inductive Coupling RFID System Design Parameter
1) Magnetic field strength: H (A/m)
This is an index to determine near field strength forms around coil when electric current is sent
from coil antenna. In HF RFID system it is transmission output.
Definition for strength in each ISO standard is as below.
- ISO/IEC 14443: 1.5A/m rms ~ 7.5A/m rms
- ISO/IEC 15693: 150mA/m rms ~ 5A/m rms
Simply, user can calculate magnetic field strength from point X (Rectangular conductor loop:
Length (a) X Width (b)) using below formula.
Confidential 17
⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜
⎝
⎛
++
+⋅
++
⋅⋅=
2222222 )2
(
1
)2
(
1
)2
()2
(4 xbxaxba
abINHπ
Through above formula, user can find out number of windings (N) and current (I). (N) and (I)
are in proportion to (H).
2) Couple Coefficient: k
Mutual inductance is a quantitative description of the flux coupling of two conductor loops. The
coupling coefficient k is introduced so that we can make a qualitative prediction about the
coupling of the conductor loops independent of their geometric dimensions.
21 LLMk⋅
= M: Mutual inductance
TRH03XM COOK BOOK
Coupling coefficient changes from 0 and 1. 1 means coupling and 0 means not coupled.
From below formula, if either one antenna is smaller than the other, coupling coefficient becomes
smaller.
.
readerTag rr ≤ / ( )322
22
readerreaderTag
readerTag
rxrr
rrk
+⋅⋅
⋅≈
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readerTag rr ≥ / ( )322
22
TagreaderTag
readerTag
rxrr
rrk
+⋅⋅
⋅≈
Contactless smart card is produced in ID-1 size standard. Considering above coupling
coefficient, produce reader system antenna in ID-1 size as default size. Since couple coefficient is
high user can expect improved reading distance. In case of designing non-standard ID-1 size
antenna (bigger or smaller), 3ALogics recommends antenna size to be within 0.5x or 1.5x of ID-1
size.
3) Resonance
Reader and Tag antenna resonance frequency should be 13.56MHz, but there is a variance of
about 1~5MHz for multiple cards anti-collision reading. The reason for this variance is multiple
tags affects reduction of resonance frequency. Also it could be due to dielectric constant by
human hands.
(Reference: Reader Resonance – Chapter 4)
3.3 Antenna Design
Loop antenna is comprised of conductive material in coil shape. Antenna size with coupling
coefficient consideration is already mentioned in above. Most misunderstood part of antenna
design is in coil length. In UHF, antenna length should be 1/2 of wavelength (λ), but for HF,
using same formula then antenna coil must be 11m. Thus, this is not a proper way. Based on
numerous design experiences, 3ALogics recommends coil winding numbers should be optimized
to have 1μH ~ 2μH inductance variance for optimum performance.
TRH03XM COOK BOOK
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3.4 Designed Antenna Radiation Pattern
If antenna physical dimension is determined, antenna simulation is necessary. However,
antenna is similar to standard ID-1 size and inductance is same as above mentioned, actual
antenna performance will be stable without simulation process. This document does not provide
explanation on simulation. This document provides examples radiation pattern of simulation
result. Picture 3-2 is antenna coil pattern before simulation. It uses Zeland’s IE3D antenna
simulation tool.
Picture 3-2 Coil Antenna
Picture 3-3 is Coil Antenna radiation pattern.
Confidential 19
Picture 3-3 Coil Antenna Radiation Pattern
TRH03XM COOK BOOK
Chapter4 Antenna Matching Optimization
and Application
4.1 TRH03XM Antenna Matching Scope
TRH03XM transmitter/receiver layer analog off-chip basic configuration is as below Picture 4-1.
Transmitter comprises of EMC filter (that converts square wave to sine wave and simultaneously
amplifies analog signal and eliminating high frequency noise, antenna, matching layer, and
antenna coil. Receiver comprises blocks of attenuator (adjusts data received through antenna to
chip input dynamic voltage range(≤ 3.6Vpk-pk)), and high pass filter (eliminating dc offset and re-
adjust half VDD(VMID) offset voltage).
R2
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Picture 4-1 Analog Off-chip Component
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Picture 4-2 displays Transmitter related equivalent circuit using Zload. Load 15Ω is optimum
impedance value for TRH03XM minimum noise, maximum gain, and maximum output power.
Transmitter Zload should not exceed 15Ω when designing.
Picture 4-2 TRH03XM Optimum Load Impedance
For HF RFID applications, direct matching is preferred over of 50Ω impedance matching for
ordinary RF system coil antenna.
(Reference: Chapter 5 covers 50Ω matching method using RF coaxial cable and Balun device.)
Confidential 21
TRH03XM COOK BOOK
4.2 EMC Filter Impedance
Picture 4-3 displays Zload conversion process by EMC filter. Impedance conversion occurs by L0a
from 1 to 2 and C0a from 2 to 3. For antenna applied to next layer by EMC filter impedance
value should be matched with 500Ω.
- 1: 15Ω, 2: 15 + j85 3: 500Ω
(a) TRH03XM and EMC filter impedance (b) Smith Chart
Picture 4-3 Impedance Transition (By EMC filter / 15Ω from 500Ω to)
EMC filter is LC type low-pass filter that is designed with 13.56MHz resonance frequency (fres).
For example when EMC filter series inductor value is 1μH, parallel capacitor value is 136pF, and
when series inductor value is 2.2μH then parallel capacitor value should be 47pF.
LCfres π2
1=
EMC filter is critical for high frequency noise elimination. Coil type having high Q is ideal for
inductor.
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4.3 Directly Antenna Matching Method
1) Antenna Coil impedance measurement
To match HF loop antenna first user must measure inductance (L) and resistance (R) value of
antenna. L and R value can be measured using Network Analyzer and to minimize TX1 and TX2
coupling error, connect TX1+TX2 instead of TX1+GND and TX2+GND to measure. (See Picture 4-
4)
Network Analyzer EX) Agilent / 8753ES
Picture 4-4 Antenna Impedance Measurement
2) Antenna matching
Measured value are L/2 = Lanta = Lantb, R/2 = Ranta = Rantb. As seen on Picture 4-5, antenna
should be equivalent. C2a, C2b and antenna coil (Lanta, Lantb) are resonant. EMC filter is
connected to C1a and C1b. (C1a, C1b: 15pF ~ 47pF)
Confidential 23
Picture 4-5 Antenna matching schematic
TRH03XM COOK BOOK
Ranta and Rantb determine antenna Q factor and value is higher than Q value is lower and if
value is lower than Q value becomes high. (Reference: 4-5 Antenna and Q factor)
Picture 4-6 Smith-chart Antenna Matching
Picture 4-6 is process of antenna matching to 500Ω in Smith-chart. Impedance changes to 500
Ω by parallel capacitor C2 to point 2 and series capacitor C1 to point 3.
3) Antenna matching results
Measuring TX1+GND using Network Analyzer after antenna matching displays result (Picture 4-7)
to 500Ω.
Picture 4-7 TX1 Measure Result after Antenna Matching
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4.4 EMC filter and matched antenna
After antenna 500Ω matching is complete, combine EMC filter and matched antenna to tune C2a.
Finally, tuning is to find a point where reading distance is the highest point by moving tag into
the antenna and should be kept within ± 10pF. Picture 4-8 displays measure point after final
tuning.
Picture 4-8 EMC Filter & Matched Antenna Measure Point
Picture 4-9 displays measure result that optimum impedance value is Zload≤15Ω.
Confidential 25
Picture 4-9 EMC Filter and Matched Antenna Measure Result
TRH03XM COOK BOOK
4.5 Receiver Configuration
Receiver is simpler configuration compared to transmitter. Refer to Picture 4-10 below.
Receiving signal from antenna and through R1, signal is reduced. By C3, R2 and R3 re-adjust DC
offset to adjust chip internal voltage as well as reduce voltage. C4 is bypass capacitor to stabilize
VMID voltage and functions as VMID voltage medium value of plus and minus in internal chip
function.
Picture 4-10 Receiver Schematic
C3, R3 and C4 should be 1nF, 820Ω and 100nF accordingly. R1 and R2 are flexible based on
each system board. RX input dynamic voltage range is ≤ 3.6Vpk-pk and will operate even with
weak voltage input. However, for receiving efficiency RX input should be high. Considering
receiving efficiency and tag reading percentage, minimum entry should be 2.7Vpk-pk, and 3ALogics
recommends RX input signal to be adjusted to 3.0~3.3Vpk-pk.
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4.6 Antenna and Q factor
From HF reader antenna C1a, C1b, Rexta, Rextb, Ranta and Rantb determine Q factor. Basically Q
factor is adjusted through C1a and C1b, thus, Rexta and Rextb use 0Ω. When Q factor value is
high, high power is delivered, but when bandwidth is reduced, bit rate error can occur.
Conversely, when Q factor value is small, bandwidth will increase but delivered power is reduced,
thus, tag reading distance can be reduced. Therefore, finding optimum Q value for antenna
matching process is very important.
Picture 4-11 Antenna Q Factor
Below Chart 4-1 displays relationship between C1a/C1b and Q factor and Ranta/Rantb and Q
factor.
Chart 4-1 Q factor, Band Width & C1, Rant
C1a, C1b ↑ ↓ Ranta, Rantb ↑ ↓
BW ↓ ↑ BW ↑ ↓
Q ↑ ↓ Q ↓ ↑
Confidential 27
TRH03XM COOK BOOK
Chapter5 How to Design 50Ω Matching Circuit using
Balun
5.1 Scope
HF RFID tag using 13.56MHz frequency energy source is RF system electric field not
electromagnetic waves. Antenna capability is determined by how well electric field energy source
allows current flow to run smoothly for energy transfer efficiency. For Ordinary HF RFID system
antenna matching uses direct matching method. Not like RF system generating electromagnetic
waves, frequency is low and current is transferred to antenna coil to generate electric field.
However, distance between system and antenna is lengthened, there could be some damages.
This document separates directly matching and 50Ω matching by 13.56MHz frequency
wavelength (λ=22m) 1/10th value (approximately 1m).
(Reference: 3ALogics Product RFLEV01)
(a) Direct Antenna Matching
(b) 50ohm Matching
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Picture 5-1 Antenna Matching Summary Chart
TRH03XM COOK BOOK
www.3ALogics.com | Confidential 29
.2 Balun and Antenna Circuit
1) Balun Related Circuit
alun used in HF antenna matching is coil type transformer that converts Balanced input(TX1,
T
5
B
X2) to Unbalanced output(1port antenna). It converts differential analog signal to single ended
analog signal and supply voltage to antenna through RF cable. Therefore, when system board
(RF module) and Antenna are apart, they can be connected using RF cable. Picture 5-2 is Balun
related circuit. It connects analog differential signal (EMC filter output) and receiver circuit and
for final layer configuration, SMA for RF cable connection.
(a) RF Modul (Analog off-chip) e
(b) Balun Circuit
Picture 5-2 Balun Related Circuit
TRH03XM COOK BOOK
2) Antenna Configuration
Picture 5-3 displays antenna circuit comprises of series capacitor for analog signal connection
and matching and parallel capacitor for resonance.
Picture 5-3 50Ω Matching Antenna Schematic
5.3 Matching Process
#3 and #5 pin are TX1 and TX2 (From Picture 5-2). When measured using Network Analyzer,
tune C15, C17, C13, and C14 to be 50Ω as seen below Picture 5-4.
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Picture 5-4 50Ω Matching Process
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5.4 Measurement
Picture 5-5 displays measurement using Network Analyzer. User can confirm TX1 and TX2 are
matched to 50Ω.
Picture 5-5 TX1, TX2 Measurement
Picture 5-7 displays TX1 and TX2 exact summation through Balun.
(a) 50ohm Matching Antenna (b) Direct Matching Antenna
Picture 5-6 Analog Signal Measured through Antenna
Confidential 31
TRH03XM COOK BOOK
5.5 Gerber
(a) 50Ω Matching Antenna
(b) Balun Circuit
Picture 5-7 50Ω Matching Circuit Gerber
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Chapter6 How to use TX Power Boost Up
6.1 Power Boost Up
Transmitter power boost up is not a necessary application for contactless smartcard standards
such as ISO/IEC 14443 and 15693. For security measurement contactless smartcard limits reading
distance. However extending RFID application to ISO/IEC 18000-3, meaning changes. ISO/IEC
15693 standard use ISO/IEC 18000-3 thus supports long range mode. Therefore, for long range
reading distance using ISO/IEC 15693 protocol, need to amplify transmitter output. As displayed
in Picture 6-1, power boost up configures system using external AMP layer. Also larger antenna
is used compared to standard card size antenna.
Picture 6-1 Power boost-up Chart (3ALogics RSK 200L)
Power boost up design covered in this page is same as RF power amplifier design using NMOS
amplifier (NXP: BLF245). Before setting devices on PCB board, circuit and device level simulation is
necessary. Important point from this simulation is devices signifying DC and AC characteristics
parameter. Next point to be covered is design method of most important active device, MOS,
parameter characteristics.
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6.2 MOS Model Power Booster Design
1) MOS Model
To design Power booster, user must select MOS in consideration with temperature, operating
frequency, gain, etc. After selecting MOS, there are two ways; designing model with given
reference design and designing using S2P file. This document explains designing using ADS
(Advance Design System) tool. Instead of designing MOS modeling, import spice model offered
with RSK evaluation kit. MOS model imported to ADS is as follows in Picture 6-2.
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Picture 6-2 Imported MOS Model
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To check if accurate model is imported compare I-V curve characteristics in MOS datasheet
through I-V curve tracer. As in Picture 6-3, user can confirm I-V curve characteristics are similar
or equal to simulation.
Picture 6-3 I-V Curve Characteristics Comparison (Simulation & Datasheet)
2) DC Bias Circuit
DC bias points are different by designed device usage. As in Picture 6-4, select optimum power
booster point by higher output power & higher efficiency.
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Picture 6-4 DC Bias Point
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Use high capacity DC block capacitor (Ideal) for input and output, and DC feed inductor (Ideal)
for bias layer. Also as seen on Picture 6-5, DC bias circuit such as voltage divider.
Picture 6-5 Bias Circuit
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3) Stability
To maximize power booster output for maximum power gain from MOS, Simultaneous
Conjugate Matching design is necessary. For Simultaneous Conjugate matching MOS
unconditional stability is a must. Stability can be predicted using MOS S-parameter, and
parameter for MOS stability prediction is K factor.
22112
2222
211
2
1
SS
SSK
Δ+−−=
21122211 SSSSΔ = −
K>1 is unconditional stability, and K<1 is conditional stability. Picture 6-6 displays stable region
from each condition.
(a) Conditional Stability Area (K<1)
(b) Unconditional Stability Area (K>1)
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Picture 6-6 Stability
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If specific frequency escapes stable region, becomes ΙΓinΙ>1, ΙΓoutΙ>1, thus, power booster
oscillates. For oscillation removing method there are; using resistor in transmitter/receiver
(Picture 6-7), using source feedback inductor, using bias capacitor, and use gate-drain feedback.
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in
out
in
out
in
out
in
out
Picture 6-7 Removing Oscillation Using Input/Output Resistor
When using input resistor, matching performance is improved and oscillation is removed easily
but noise characteristics becomes worse, thus, not often used for circuit design with importance
in noise characteristics such as LNA (Low Noise Amplifier). When using output resistor, Linearity
is improved and oscillation is removed but loss in power output occurs, thus, not recommended
for power amplifier. Using source feedback (Picture 6-8) method picks up impedance matching
in all areas and seizes oscillation reducing AC elements from gate-drain feedback.
Picture 6-8 Removing Oscillation using Source, Gate-Drain Feedback
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Based on above oscillation removing method, stability circuit is configured using input resistor in
power booster circuit and bypass capacitor in DC bias.
Picture 6-9 Stability Circuit
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From the result (Picture 6-10) user can confirm unconditional stability region.
(a) Stability (Before Removing Oscillation)
(b) Stability (After Removing Oscillation)
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Picture 6-10 Power Booster Circuit Stability
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4) Input and Output Matching and Measurement
For input/output matching, user must determine using of conjugate matching (both
input/output), not conjugate matching (output only) or load-pull. All these are to enhance
stability. Next explanation will be about power booster matching is input/output conjugated
matching method. Picture 6-11 is a circuit for input matching.
Picture 6-11 Input Matching Circuit Picture 6-12 is result of input matching. Approximately setting at 50Ω, through input/output
matching tuning to 50Ω matching.
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Picture 6-12 Simulation Result after Input Matching
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Picture 6-13 is output matching circuit configured with DC block and T-matching.
Picture 6-13 Output Matching Circuit
After Input/output matching, input/output conjugate matching result is seen as Picture 6-14.
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Picture 6-14 Simulation Result after Input/Output Matching
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Up to this point, simulation was done using ideal components but should go through new
tuning process using actual component that will be used. Power booster final measure result
after tuning process is as seen on Picture 6-15.
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Picture 6-15 Power Booster Measurement Result
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6.3 Power Booster Design Using S2P File
1) S2P File Extract
To design power booster using S2P file, first obtain S2P file from MOS manufacturer and create
same bias circuit then go through simulation. Or, create bias circuit then extract S2P file.
Picture 6-16 displays S2P file extracting steps using Network Analyzer.
Picture 6-16 S2P File Extracting Steps
Picture 6-17 displays parts of extracted S2P file format through above process.
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Picture 6-17 Extracted S2P File
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2) Input/Output Matching and Measurement
When designing power booster using S2P file, bias circuit is not necessary since bias information
is included in S2P file. Picture 6-18 displays stabilization process and status after input/output
matching.
Picture 6-18 Input/Output Matching Circuit
Picture 6-19 displays simulation result using actual component.
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Picture 6-19 Simulation Result after Input/Output Matching
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Picture 6-20 is final measurement result after power booster configuration. Actual simulation
may not be exactly the same.
Picture 6-20 Power Booster Measurement Result
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(Reference: Above mentioned power booster circuit, actual board and system can be confirmed
using RSK200L evaluation kit.)
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Chapter7 EMC Problem Solving
7.1 EMC (Electromagnetic Compatibility) Scope
EMC is capability to co-exist in electromagnetic waves environment with acceptable performance
without signal data loss as well as not impacting electromagnetic waves disorder to surrounding
environment.
Picture 7-1 EMC Classification
EMC classification is as seen on above Picture 7-1. For actual certification testing process EMI
Test classified as intra-system EMC. Not only for EMI but also for application area specification
and measuring elements are different. Major measuring element, EMI
(Electromagnetic Interference), is divided into CE/RE (Conducted/Radiated Emission) and
CS/RS(Conducted /Radiated Susceptibility) that electromagnetic waves can inflict system
erformance reduction.
- DM: Differential-Mode Interference
p
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- CM: Common-Mode Interference
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.2 Electromagnetic Waves Radiation Standard
standards are different. Below
art lists electromagnetic waves allowance by Class A and B.
: For exact standard please check electromagnetic waves limitation standards from each
untry)
Chart 7-1 Electromagnetic aves Radiation Standard
7
By each country and region electromagnetic waves radiation
ch
(Reference
co
W
Classification Measure Dist (m) Frequency (MHz) Allowance (dBµV/m)
A class 10m 230 ~ 1,000 47
20 ~ 230 40
B class 10m 230 ~ 1,000 37
20 ~ 230 30
7.3 EMI Noise Measure
1) Noise Measure Basis
se by configuring circuit to control noise cause
nd transfer factor and eliminating mixed in noise.
2) Noise Measure Technology
ed when designing circuit. Basic technology is PCB design and
circuit design for noise isolation.
Basic three noise measures are; ‘do not create noise’, ‘do not transfer noise’ and ‘do not respond
to noise’. Basically noise measure is to remove noi
a
If user knows noise source, removing method is not so difficult. However, basic noise control
design technology must be appli
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For EMI noise control technology methods are in Picture 7-2 below.
TIME COST
Control
Technology
Selecting At Initial Design Low Cost
Layout
Routing
Impedance matching
Isolation
Grounding
Filtering
Shielding Possible to append Expensive
Picture 7-2 EMI Noise Measure Technology Type
7.4 Reader System Design with EMI Noise Consideration
1) System Noise Origination with TRH03XM
TX1 and TX2 are signal ports with highest operating capacity in TRH03XM chip and output
square wave. Square wave signal includes original frequency and high frequency noise. Crystal
oscillator and MCU interface data line also create noise but TX1 and TX2 ports are the most
potential noise creating reason.
2) Component Selection and Filtering
TX1 and TX2 signals should be filtered and converted to analog signal before sending to
antenna. At this point most important factor is Q value of EMC filter. Based on this value, high
frequency noise can be controlled.
- L = 1μH (TDK NL322522T – 1R0J / Q =30)
- C = 68pF (Tolerance ≤ 2%)
Inductor in EMC filter is recommended to use high Q wire wound inductor and low tolerance
capacitor.
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RX
TX1
TX2
VMID
1uH
1uH
68pF 68pF
68pF 68pF
15pF
15pF
120pF
120pF
39pF
39pF
0
0
0
0
3.0k
820
100nF
1nF1.0k
Picture 7-3 Analog Off-chip Component (RSK board)
3) Layout and Routing
- Arrange TX1/TX2 pin and inductor in EMC filter as close as possible
- Avoid via hole where transmission line pass through analog signal.
- Layout TX1 and TX2 symmetrically
(a) (b) (c)
Picture 7-4 Transmitter Off-chip Placement Example
Picture 7-4 (a) displays using via hole in signal line (Not recommended), (b) displays EMC filter
away with ferrite chip inductor with bad Q value, and (c) displays correctly designed Transmitter.
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4) Shielding
By inserting ground line between signals it reduces high voltage transmission signal
interference and receiver signal interference.
GND
GND
GND
GND
TX2/ANT2
TX1/ANT1
RX_in
GND
GND
GND
TX2/ANT2
TX1/ANT1
RX_in
TX2/ANT2
TX1/ANT1
RX_in
(a) (b) (c)
Picture 7-5 Antenna Connection Example
As seen in Picture 7-5, when inserting ground signal between signal lines as (a) and (b), signal
extension and ground shielding for wiring will automatically occur. (c) is not recommended.
Below Picture 7-6 displays antenna coil and ground shield pattern. Antenna connector and
matching circuits should be as close as possible. To reduce electric field insert ground shielding
patter (Picture 7-6) is inserted.
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Picture 7-6 Antenna Coil and Ground Shield Pattern
TRH03XM COOK BOOK
Antenna should use more than 2 layer board and to minimize EMI noise and electrical field use
4 layer board. Picture 7-7 displays RSK board antenna Gerber using 2 layer board. It is
optimized antenna pattern with coil and signal line (TOP) and shield pattern (BOTTOM).
(Card size: ID1 size, ISO/IEC 7810)
(a) TOP layer
(b) Bottom layer
Picture 7-7 Card Size Antenna Coil Gerber Example (2 Layer)
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5) Other Considerations
If EMI noise measure is executed as guided on previous chapter, noise from Reader IC will be
under control. For example Picture 7-8, displays improved performance of EMC filter inductor
replacing ferrite chip inductor to high Q value wire wound inductor.
(a) Above Standard Noise (b) Below Standard Noise
Picture 7-8 EMI Noise Examples
When noise spacing is 13.56MHz, user can assume the noise is from Reader IC transmitter.
Other noise can be predicted that it comes from MCU interface line or power source. Place EMI
device to suspicious interface I/O or power source, or using 4 layer to strengthen shield pattern
will help reduce noise.
(Reference: Place wire antenna to suspicious I/O to amplify noise element to locate noise
origination.)
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Chapter8 Air interface Measurement
8.1 Air interface
Air interface, when RF Transceiver is configured, is a gage to know whether Analog part PHY
(physical layer) satisfies electrical specifications. Air interface exact waveform standard are listed
in each protocol documents. However, protocol test standard document do not list exact
waveform test method in air interface but using standard documentation, air interface waveform
test method and actual results are listed. ISO/IEC air interface standard can be confirmed using
TRH03XM to enhance credibility and understanding functionality of Reader IC.
8.2 Measurement
Between reader and tag communication, confirm transmitted data to trigger signal in reader
and antenna voltage from modulation.
Tektronix TDS5104B
(a) Antenna equivalent model (b) Equipment (Oscilloscope)
Picture 8-1 Measurement Point
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8.3 100% ASK Waveform
1) ISO/IEC 14443A
(a) ISO/IEC 14443A (b) RSK Board Modulation Waveform
Picture8-2 100% ASK Modulation Waveform
Chart 8-1 100% ASK Modulation Index
RSK Board Results ISO/IEC 14443 Specification
t1 2.32μs 2 ~ 3μs
t2 0.74μs 0.7 ~ 3μs
t3 0.36μs 0 ~ 1.5μs
t4 0.22μs 1 ~ 0.4μs
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2) ISO/IEC 15693
(a) ISO/IEC 15693 (b) RSK Board Modulation Waveform
Picture 8-3 100% ASK Modulation Waveform
Chart 8-2 100% ASK Modulation Index
RSK Board Results ISO/IEC 15693 Specification
t1 9.36μs 6 ~ 9.44μs
t2 8.72μs 2.1 ~ 9.44μs
t3 0.48μs 0 ~ 4.5μs
t4 0.34μs 0 ~ 0.8μs
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8.4 10~30% ASK Waveform
1) ISO/IEC 14443B
(a) ISO/IEC 14443B (b) RSK Board Modulation Waveform
Picture 8-4 10% ASK modulation waveform
Chart 8-3 10% ASK modulation Index
RSK board results ISO/IEC 14443 specification
tf 0.34μs 2μs max
tr 0.34μs 2μs max
hf, hr 0.2v 0.4v max
Modulation
Index
10%
(6 ~ 45 %) 8 ~ 14%
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2) ISO/IEC 15693
(a) ISO/IEC 15693 (b) RSK Board Modulation Waveform
Picture 8-5 10% ASK Modulation Waveform
Chart 8-4 10% ASK modulation Index
RSK Board Results ISO/IEC 15693 Specification
t1 9.4μs 6 ~ 9.44μs max
t2 9.16μs 3 ~ 9.44μs
t3 0.36μs 0 ~ 4.5μs
hf, hr 0.2v 0.4v max
Modulation
index
10%
( 6 ~ 43 % ) 10 ~ 30%
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Chapter9 Modulation Index Control
9.1 Modulator Concept
TRH03XM transmitter driver comprises of main driver transferring tag electric power and
modulation driver that controls modulation index.
Picture 9-1 Transmitter Driver Block Diagram
Chart 9-1 Transmitter Control Register Map
Address Name Initial Description Value
7 6 5 4 3 2 1 0
0x11 Txcontrol 58 • Antenna driver control 0 Modulator
source
ASK
100
TX2
inv
TX2
nomod
TX2
en
TX1
en
0x12 Cwconductance 3F • Antenna driver conductance 0 0 Cwconductance
0x13 Modconductance 04 • Modulation Conductance 0 0 Modconductance
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This two drivers are controlled by Txcontrol register[0x11] and each driver output is controlled
by [0x12], [0x13] register that controls conductance. As in Picture 9-2, (a) 100% ASK modulation
occurs by main driver switching, (b) 10% ASK modulates by main driver and modulation drivers
elected signal.
MainModulation
TX_I TX_ANT
(a) 100% ASK Waveform (b) 10% ASK Waveform
Picture 9-2 ASK Modulation Waveform
9.2 Modulator Index Adjustment
1) Standard Modulation Index
- ISO/IEC 14443 A type: 100%
- ISO/IEC 14443 B type: 8% ~ 14%
- ISO/IEC 15693: 100% or 10% ~ 30%
- ISO/IEC 18092 and Felica: 8% ~ 30%
(For other protocols please refer to each protocol modulation index.)
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2) Modulation Index Control
Modulation index can be adjusted using register [0x13]. Adjustment is for all standard
specifications except basic 100% ASK switching operation.
Chart 9-2 TRH031M Modulation Index (3ALogics TEST board)
Value Index (%) Value Index (%) Value Index (%)
01 25.7 16 4.1 2B 2.9
02 18.6 17 3.2 2C 3.6
03 9.5 18 5.4 2D 2.9
04 14.2 19 4.0 2E 2.8
05 8.5 1A 3.9 2F 2.3
06 7.7 1B 2.9 30 4.8
07 5.4 1C 3.6 31 3.7
08 12.9 1D 2.9 32 3.6
09 7.7 1E 2.8 33 2.9
0A 7.0 1F 2.2 34 3.4
0B 5.1 20 8.9 35 2.8
0C 6.5 21 6.0 36 2.6
0D 4.8 22 5.7 37 2.3
0E 4.5 23 4.1 38 3.2
0F 3.4 24 5.3 39 2.6
10 11 25 4.0 3A 2.6
11 7.0 26 4.0 3B 3.9
12 6.3 27 3.4 3C 2.5
13 4.8 28 5.0 3D 2.2
14 6.0 29 3.9 3E 2.0
15 4.3 2A 3.7 3F 1.7
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Chart 9-3 TRH033M Modulation Index (3ALogics TEST board)
Value Index (%) Value Index (%) Value Index (%)
01 41.9 16 6.5 2B 4.8
02 30.9 17 5.6 2C 5.1
03 18.7 18 7.8 2D 4.5
04 23.7 19 6.5 2E 4.3
05 15.0 1A 6.1 2F 3.9
06 12.9 1B 5.1 30 6.5
07 9.6 1C 5.6 31 5.6
08 18.9 1D 5.0 32 5.1
09 12.7 1E 4.7 33 4.5
0A 11.0 1F 4.2 34 4.8
0B 8.5 20 12.9 35 4.2
0C 9.7 21 9.6 36 4.0
0D 7.8 22 8.5 37 3.5
0E 7.2 23 7.2 38 4.5
0F 6.1 24 7.8 39 4.0
10 15.2 25 6.5 3A 3.9
11 10.9 26 6.1 3B 3.4
12 9.4 27 5.3 3C 3.7
13 7.8 28 7.0 3D 3.2
14 7.7 29 6.0 3E 3.1
15 7.0 2A 5.6 3F 2.7
Chart 9-2 and 9-3 are measured value maximizing (a) Cwcondutance [0x12: 3F] and adjusting
Modconductance [0x13]. These values are based on 3ALogics boards offered as RSK board. If
applied to different system, these values may differ because antenna, components, and other
conditions are not the same.
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9.3 Adjustment Guide
Modulation index can be adjusted using 6 bit total of 64 steps but not all values are used.
Based on system and antenna size these values differ but user can use Chart 9-4 and 9-5 as
reference when using similar size antenna. Use as Quick Guide these value meet air interface
standard by protocol and there are total of 10 steps with 01~3F.
Chart 9-4 TRH031M Modulation Index Adjustment Quick Guide
(a) Small size antenna: 45mm X 35mm, for digital door lock
Value 01 02 04 08 10 20 21 30 31 3F
Index
(%) 14.6 11.6 9.8 8.3 7.1 5.7 4.1 3.5 2.9 1.6
(b) Medium size antenna: 75mm X 50mm, Card and ID-1 size
Value 01 02 04 08 10 20 21 30 31 3F
Index
(%) 25.7 18.6 14.2 12.9 11 8.9 6.0 4.8 3.7 1.7
(c) Large size antenna: 75mm X 75mm, ISO/IEC 15693 extended reading distance
Value 01 02 04 08 10 20 21 30 31 3F
Index
(%) 18.3 14.1 11.6 10.0 8.5 6.9 5.0 4.1 3.3 1.7
RSK100 setting [0X13]
- ISO/IEC 14443 B-type: 04
- ISO/IEC 15693: 00 or 10
(Set 100% ASK protocol with 00)
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Chart 9-5 TRH033M Modulation Index Adjustment Quick Guide
(a) Small size antenna: 45mm X 35mm, for digital door lock
Value 01 02 04 08 10 20 21 30 31 3F
Index
(%) 28.7 19.3 14.2 11.1 9.2 8.1 6.2 4.5 4.0 2.6
(b) Medium size antenna: 75mm X 50mm / Card , ID-1 size
Value 01 02 04 08 10 20 21 30 31 3F
Index
(%) 41.9 30.9 23.7 18.9 15.2 12.9 9.6 6.5 5.6 2.7
(c) Large size antenna: 75mm X 75mm / ISO/IEC 15693 extended reading distance
Value 01 02 04 08 10 20 21 30 31 3F
Index
(%) 34.5 24.2 17.6 13.8 11.0 9.6 7.3 5.3 4.7 2.5
RSK300 setting [0x13]
- ISO/IEC 14443 B-type: 10
- ISO/IEC 15693: 00 or 10
- Felica: 10
(Set 100% ASK protocol with 00)
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Chapter10 Understanding Demodulation
Actions
10.1 What is Demodulation?
Demodulation is simply the conversion of a modulated carrier wave into a current equivalent to
the original signal. Demodulation is the act of removing the modulation from an analog signal
to get the original baseband signal back. Demodulating is necessary because the receiver system
receives a modulated signal with specific characteristics and it needs to turn it to base-band.
There are several ways of demodulation depending on what parameters of the base-band signal
are transmitted in the carrier signal, such as amplitude, frequency or phase.
Picture 10-1 HF RFID Demodulation Overview
Picture 10-1 is simple demodulation overview. It’s half duplex data transfer method that
displays modulation by reader modulation and tag load modulation while energy is supplied
continuously. Data demodulation by this load modulation is major role of reader receiver.
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10.2 Demodulation Register
Chart 10-1 is Receiver control register map. VGA (Variable Gain Amplifier) is a block to amplifier
minute analog signal that rectified through rectifier and able to change gain value. From average
RF system RSSI (Received Signal Strength indicator) receives feedback data by strength of receiver
signal and automatically changes AGC (Automatic gain controller) gain, but HF RFID system does
not automatically change gain. It’s because load modulation data signal is not consistent based
on distance and strength of RX carrier wave as well as maximum strength receiver can receive is
pre-determined. Basically received strength and size of carrier wave do not impact data size.
System without noise set gain [0x19] to maximum value of 05 without any harm but typically set
to 03. To maximize performance user can adjust in software level setting gain from 00 to 05.
Chart 10-1 Receiver Control Register Map
Address Name Initial Description Value
7 6 5 4 3 2 1 0
0x19 Rxcontrol1 02
• VGA gain control
( filter default gain : 27.6dB )
101 – 21.58dB, 100 – 20.00dB
011 – 18.06dB, 010 – 15.56dB
001 – 12.04dB, 000 – 06.02dB
0 0 0 0 0 VGA gain
0x1C Rxthreshold 18
• Comparator reference voltage control
101 – 1.560v, 100 – 1.591v
011 – 1.621v, 010 – 1.681v
001 – 1.713v, 000 – 1.743v
• Hysteresis range (peak to peak)
101 – 256mv, 100 – 216mv
011 – 180mv, 010 - 144mv
001 – 106mv, 000 – 068mv
0
Com.
Ref.
On
Hysteresis
range
Comparator
Ref. voltage
Comparator is a block to convert analog signal to digital signal. Reference voltage is not used
unless external components filtering are not adequate or impact of offset is big. Hysteresis range
is used to protect data from changes affected by noise. Threshold is increased and decreased
to reduce noise. Basically register[0x1C] value is set to 18.
(Comparator: 000 / Hysteresis range: 011 / Comparator reference voltage control On: 0)
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RSK 100 setting [0X19] / [0X1C]
- ISO/IEC 14443 A-type: 03 / 18
- ISO/IEC 14443 B-type: 03 / 18
- ISO/IEC 15693: 03 / 18
- Tag-it: 03 / 18
RSK 300 setting [0X19] / [0X1C]
- ISO/IEC 14443 A-type: 03 / 18
- ISO/IEC 14443 B-type: 03 / 18
- ISO/IEC 15693: 03 / 18
- Tag-it: 03 / 18
- I-CODE: 03 / 18
- Jewel: 03 / 18
- Inside: 03 / 18
- Felica: 01 / 5A and 01 / 18 and 01 / 5B register value sweep
Receiver register setting for all protocols (except Felica) are same. Compared to other
protocols, Felica frequency carrier wave is low and amplitude change by load modulation is very
small. For various Felica tag reading, register value change is necessary. Only for Felica protocol
switch comparator reference value from default value up and down for use. For RSK board as an
example, fix Gain to 12.04dB and Hysteresis range to 180mV but change comparator reference
value.
TRH03XM COOK BOOK
10.3 Demodulation Signal Measurement
1) Measurement Set up
Demodulation signal can be surveyed using TRH03XM #1 pin TESTOUT. As seen on Picture
10-2, change register [0x26] to select signal for probing.
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Test output control
TESTOUT
LOW
HIGH
Card response envelope signal
Decoded signal
Coded signal
Oscilloscope probing
< Register Address : 26H >
<00>
<01>
<02>
<03>
<04>
Card detector output
<05>
Picture 10-2 TEST Output Control Block Diagram
(Register 05 value only applies to TRH033M chip.)
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2) Measurement
TESTOUT (26H: 02 , ENVELOPE SIGNAL) TX1 ANTENNA
- ISO/IEC 14443 A-type (Manchester / OOK 847kHz subc.)
(a) A-type Card Response
(b) Envelope Signal
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Picture 10-3 14443A Demodulation Waveform
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- ISO/IEC 14443 B-TYPE (NRZ / BPSK SUBC.)
(a) B-type Card Response
(b) Envelope Signal (Phase Shift Section)
Picture 10-4 14443B Demodulation Waveform
- ISO/IEC 15693 (Manchester / OOK subc.)
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(a) 15693 Card Response
(b) Envelope Signal
Picture 10-5 15693 Demodulation Waveform
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TRH03XM COOK BOOK
Chapter11 Using Card detector
11.1 Card Detector Principle
As seen in Picture 11-1, Card detector generates carrier wave only without modulation for data
transmission from reader. When tag is not available, original power output is transmitted
through antenna, but when tag is available, antenna current flows reversely to mutual inductance
by tag coil, thus, carrier wave (basically voltage) is lowered. Detecting voltage change is the role
of card detector.
Picture 11-1 Carrier Signal Reduction by Tag
11.2 Card Detector Application
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Card detector is effective to reduce electric power use when card does not exist. Products such
as digital door lock, locker with RF keys, PDA and handheld RFID reader that do not have
constant electric source are ideal for card detector functions.
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11.3 Card Detector Movement
1) Card Detector Basic Movement
Card detector is only available in TRH033M chip and it comprises of rectifier block, DAC,
Comparator Amp. From 3ALogics own proprietary patent, circuit converts carrier wave AC signal
to DC and compare this DC value to threshold voltage to output comparable signal. Low value,
from DC output converted by threshold voltage, to logic 0 and high value to logic 1 output to
detect card.
2) Card Detector Register Map
Card detector block control registers are listed in Chart 11-1. System applying card detector
and reference level register [0x32] impacting detection performance are 6 bit and voltage control
can be done between 1.05V to 2.25V.
Chart 11-1 Card Detector Register Map
Address Name Initial Description Value
7 6 5 4 3 2 1 0
0x32 DETECTLEVEL 00
• DAC reference level
ref vol. : 1.05 ~ 2.25 ( 1LSB 75mV )
000000 – 00 : 1.05 + 1LSB
111111 – 3F : 2.25
0 0 Detectlevel
0x33 DETECTREG 00 • Detect register
DetectOn : high enable DetectOn 0 0 DetectTime DetectFlag 0
Register[0x33] controls card detector including DetectOn (Enabling flag), DetectFlag bit (Displays
existence of card), and DetectTime flag (Store time management). Bit 0 is not used and
DetectTime can be use with Default with 00. Time delay according to DetectTime flag is listed
below.
- 000 : 5us Detection Set Time 001 : 10us Detection Set Time
- 010 : 15us Detection Set Time 011 : 20us Detection Set Time
- 1xx : 40us Detection Set Time
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11.4 Card Detector Set-up Procedure
Below is card detector set up process. To minimize power consumption while detecting only
turn on minimum driver while transmitting carrier wave.
1) 0X11: 01, 0X12: 00, 0X13: 01, 0X26: 05, 0X32: 00, 0X33: 80 Register initial value setting for
card detection
2) Receiver RX signal pk-pk confirm (#26 pin)
Example: RX 980mV
3) Change 0X13 Register for RX pk-pk signal to have more than 1.0V input: 02 04 08 10
20
Example: Change 0X13 -> 02, RX 1.12V OK
- If Register value is high than error will decrease but current consumption will slightly
increase. 02 setting is only an example. 20 is recommended.
*** But, to reduce error in sample case, if increasing current does not impact system
current consumption, 0x12 Register instead of 0x13 Register for card detection operation
is ok.
4) More than 10 test samples for RX signal pk-pk Check (Cf. EMC LC filter: High device
tolerance components used.)
Example:
1번 2번 3번 4번 5번 6번 7번 8번 9번 10번 11번 12번 13번 14번 15번
1.12 1.11 1.14 1.12 1.14 1.12 1.12 1.12 1.14 1.105 1.10 1.11 1.12 1.11 1.12
5) Select best pk-pk signal sample (For all sample case to be detected, select lowest sample
case of AC to DC conversion level)
Example: #10
6) Raise selected sample Register 0X32 (00 ~ 3F) and search for low Register value
Example: #10 00 ~ 06 -> high, 07 -> low
7) Conclude Register value from Low Register to Standard (Lower 1 to 2 steps)
Example: 05 or 06
8) Register value search complete.
Example: Register value used in Card detection
0X11: 01 - Tx control (TX2 off and TX modulator source low, 100% ASK disable)
0X12: 00 - Cw-Conductance off
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0X13: 02 - Mod-Conductance
0X32: 05 or 06 - Card detector reference voltage
0X33: 80 - Card detector enable
Card detector detects by slight voltage reduction rather than data receiving, thus, error
occurrence is high compared to sample demodulation process. Therefore, multiple sample tests
are required before register setting for improved result.
11.5 Practical Application
Using 45mm X 35mm Antenna as a standard, current system configuration detects card twice in
1 second. Enabling 1.25msec card detector for 500msec, system current consumption is 19.3mA
so total current consumption calculation is 48.25uA.
- Current Calculation
TVDD 11.5mA + AVDD: 3.2mA + DVDD: 4.6mA = 19.3mA
1.25msec X 19.3mA / 500msec = 48.25uA
Actual calculated value using Multi-meter is approximately 38uA and different from calculated
value. Calculated value is assuming 1.25msec carrier wave transmitting, and actual value detected
about 20% less current.
Picture 11-2 displays waveform measured using Oscilloscope to see card detector operation.
Depending on system and board, RST time and Carrier on time adjustment (lower) is possible and
power consumption can be reduced further.
TESTOUT : 1번 pin
RST : 22번 pin
RX : 26번 pin
1.25ms
Carrier on time : 260u
Card : X Card : O
(a) Card Not Available (b) Card Available
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Picture 11-2 Card Detector Operation Mode Waveform
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- Battery life calculation
** Ni-Cd (Nickel Cadmium): 1.5V, 700mAh ~ 800mAh
Ni-MH(Nickel-hydride): 1.5V, 2100mAh ~ 2500mAh
(What is mAh?: Current mA used in 1hr. Example: 2500mAh / 250mA = 10hr. Basically
1.5V MP3 with 250mA current consumption can use 10hrs of battery. Compared to Ni-MH,
battery use is extended for 1.5x~2x of normal battery consumption.)
** Ni-MH 1.5V 2500mAh Standard (DDL set: AA size 4 Alkaline Batteries)
Electric power 1.5V 4ea series, P = 6V X 2500mAh = 15000mWh
(Fix current since it is series)
P = 3.3V X 38uA = 125.4uW
15000mWh/125.4uW = 119617.2 hours = 4984 days = 13.65 years
RSK 300 setting
Mod-driver cwconductance / Detection carrier power [0x13]: 04
Detector reference level [0x32]: 05
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[Reference]
[1] International Standard ‘ISO/IEC 14443‘, Part II
[2] International Standard ‘ISO/IEC 15693’, Part II
[3] Young Yoon, ‘RF Active Circuit Design Theory and Practical Use’, Hongreung Science
Publishing, Chapter6, 2005
[4] Dae Jin Cho, ‘RFID Theory and Applications ‘, Hongreung Science Publishing, Chapter 1,
2005
[5] Klaus Finkenzeller ‘ RFID HABDBOOK ‘, Youngjin.com, Chapter 4, 2004
3ALogics 13.56MHz Multi-protocol RFID reader IC Cook Book
It’s RFID
RFID & Mobile SoC for Ubiquitous Technology
Contact
3ALogics Inc. 7th Fl., Hyundai-office Bldg., 9-4, Sunae-dong,
Bundang-gu, Seongnam-si, Gyeonggi-do, 463-783
Korea
TEL: (82)-(31)-715-7117
FAX: (82)-(31)-719-7551
Homepage: http://www.3ALogics.com
Email : [email protected]
Printed in the Republic of Korea.
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