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Rev. 0.3 10/12 Copyright © 2012 by Silicon Laboratories AN437 AN437 Si4432 RF P ERFORMANCE AND FCC C OMPLIANCE TEST R ESULTS 1. Introduction This document provides measurement results and FCC compliance results for the Si4432B when operated from 902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power, transmit output spectrum, transmit deviation, and conducted harmonics. The FCC compliance results demonstrate a full FCC compliance scan to FCC 15.247. All tests are performed using an ISM- DK3 kit with a 4432-DKDB1 test card.The Wireless Development Suite (WDS) is used to control the test card. The results can be duplicated by using the same configuration and scripts available on the Silicon Labs website and referenced in the EZRadioPRO Quick Start Guide. All settings were used directly from the Excel Register Calculator worksheet provided on the Silicon Labs website. For measurement results with different RF parameters, contact customer support. Silicon Labs has not attempted to obtain FCC certification on any RF reference design board using Si443x chips. FCC certification is obtained at the module level (and not the chip level), and thus any potential certification that would be obtained on Silicon Labs RF test cards would not be transferable to customer application modules. The compliance test results presented within this application note should be viewed as simply providing confidence to the customer that certification may be obtained, if the recommended RF design and layout practices are followed. 2. Relevant Measurements to comply with FCC FCC compliance in the US only pertains to output power, emissions, and harmonics. There are no receive sensitivity, selectivity or blocking measurements to comply with FCC. Two sections pertain to operation in the 902- 928 MHz band, 15.247 and 15.249. The maximum output power under FCC 15.247 is +30 dBm with Frequency Hopping Spread Spectrum. FCC 15.249 limits the maximum rms field strength to 50 mV/m at a 3 m distance which is equivalent to a radiated output power of –1.2 dBm EIRP for a non-hopping system. The TX measurements in this report assume a Frequency Hopping System operating at +20 dBm under 15.247.

ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

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Page 1: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

Rev. 0.3 10/12 Copyright © 2012 by Silicon Laboratories AN437

AN437

Si4432 RF PERFORMANCE AND FCC COMPLIANCE TEST RESULTS

1. Introduction

This document provides measurement results and FCC compliance results for the Si4432B when operated from902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking,transmit output power, transmit output spectrum, transmit deviation, and conducted harmonics. The FCCcompliance results demonstrate a full FCC compliance scan to FCC 15.247. All tests are performed using an ISM-DK3 kit with a 4432-DKDB1 test card.The Wireless Development Suite (WDS) is used to control the test card. Theresults can be duplicated by using the same configuration and scripts available on the Silicon Labs website andreferenced in the EZRadioPRO Quick Start Guide.

All settings were used directly from the Excel Register Calculator worksheet provided on the Silicon Labs website.For measurement results with different RF parameters, contact customer support.

Silicon Labs has not attempted to obtain FCC certification on any RF reference design board using Si443x chips.FCC certification is obtained at the module level (and not the chip level), and thus any potential certification thatwould be obtained on Silicon Labs RF test cards would not be transferable to customer application modules. Thecompliance test results presented within this application note should be viewed as simply providing confidence tothe customer that certification may be obtained, if the recommended RF design and layout practices are followed.

2. Relevant Measurements to comply with FCC

FCC compliance in the US only pertains to output power, emissions, and harmonics. There are no receivesensitivity, selectivity or blocking measurements to comply with FCC. Two sections pertain to operation in the 902-928 MHz band, 15.247 and 15.249. The maximum output power under FCC 15.247 is +30 dBm with FrequencyHopping Spread Spectrum. FCC 15.249 limits the maximum rms field strength to 50 mV/m at a 3 m distance whichis equivalent to a radiated output power of –1.2 dBm EIRP for a non-hopping system. The TX measurements in thisreport assume a Frequency Hopping System operating at +20 dBm under 15.247.

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2 Rev. 0.3

3. RX Measurement Results

3.1. SensitivitySensitivity measurements are done as bit error rate (BER) with BER <0.1%. To convert BER to PER it can beapproximated by adding 3 dB (PER = BER+3 dB). A modulation index of H = 1 is used for all cases, with noadditional allocation in the IF bandwidth for XTAL tolerance.

Figure 1. Sensitivity vs. Datarate

3.2. Adjacent Channel SelectivityAll selectivity results are done by positioning the input power 3 dB above sensitivity with the primary signal sourcegenerator. A second generator with an unmodulated signal is used as the interferer and combined with the primarysignal using a power combiner (e.g., Mini-Circuits ZFSC-2-4-S+). The second interferer generator is placed at thedesired frequency offset and then the power is increased until the BER degrades to 0.1% (1E-3). For example, the+1 MHz point in Figure 3 shows 62 dB of rejection. The sensitivity for 5 kbps is –116.5 dBm so the primarygenerator is set to –113.5 dBm. The secondary generator is set 1 MHz away from the primary generator and itspower is increased to –51.5 dBm where the BER degrades to 0.1% which results in a rejection of the interferer by62 dB.

Sensitivity vs Datarate

-125

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-95

1 10 100 1000

Datarate (kbps)

Sen

siti

vity

(d

Bm

)

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Rev. 0.3 3

Figure 2. 5 kbps Adjacent Channel Selectivity

Datarate = 5 kbps, Deviation = 2.5 kHz, no allocation in BW for XTAL tolerance.

Figure 3. 40 kbps Adjacent Channel Selectivity

Datarate = 40 kbps, Deviation = 20 kHz, no allocation in BW for XTAL tolerance.

Adjacent Channel Selectivity - 5kbps

-70

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-30

-20

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0

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

Frequecy Offset (MHz)

C/I

Adjacent Channel Selectivity - 40kbps

-60

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0

10

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-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

Frequency Offset (MHz)

C/I

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3.3. BlockingBlocking measurements are done with the same measurement technique as described above for the adjacentchannel selectivity but are performed at larger frequency offsets.

Figure 4. kbps Blocking

Datarate = 5 kbps, Deviation = 2.5 kHz, no allocation in BW for XTAL tolerance.\

Figure 5. 40 kbps Blocking

Datarate = 40 kbps, Deviation = 20 kHz, no allocation in BW for XTAL tolerance.

Blocking - 5kbps

-90-80-70-60-50-40-30-20-10

0

0.01 0.1 1 10

Frequency Offset (MHz)

C/I

Blocking - 40kbps

-80-70-60-50-40-30-20-10

01020

0.01 0.1 1 10

Frequency Offset (MHz)

C/I

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Rev. 0.3 5

3.4. Sensitivity vs. Frequency OffsetThe Sensitivity vs. Frequency Offset measurements are referred to as bucket curves due to the shape of the curve.The receiver and generator frequencies are calibrated for zero frequency offset. The signal generator is then offsetand the sensitivity measurement is repeated. The performance for this parameter is directly linked to theprogrammed receive bandwidth. With AFC disabled there is still internal modem compensation which corrects foroffsets up to 0.25 x RX BW and with AFC enabled offsets can be corrected up to 0.35 BW. The modem parametersand receiver bandwidths were set using the Excel Register Calculator worksheet assuming a 20 ppm CrystalTolerance on both the transmitter and receiver as shown in Figure 6.

Figure 6. Excel Register Calculator Worksheet

Figure 7 demonstrates the performance for DR = 100 kbps, Dev = 50 kHz, and a BW of 208.4 kHz. For the AFCdisabled (modem compensation only) case the frequency offset compensation can be calculated as 0.25 x 208.4 =52.1 kHz which may be observed in Figure 7. For the AFC enabled case the frequency offset compensation can becalculated as 0.35 x 208.4 = 73 kHz. If more frequency offset compensation is desired then the RX bandwidthshould be increased to a value greater than that shown in the Excel Register Calculator worksheet. This may bedone by artificially increasing the value used for XTAL Tolerance.

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Figure 7. Selectivity vs. Frequency Offset, 100 kbps

Figure 8. Selectivity vs. Frequency Offset, 40 kbps

Sensitivity vs Frequency Offset - DR=100kbps, BW=208.4kHz

-110

-100

-90

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-70

-60

-100 -80 -60 -40 -20 0 20 40 60 80 100

Frequency Offset (kHz)

Sen

siti

vity

(d

Bm

)

AFCOFF

AFCON

Sensitvity vs Frequency Offset - 40kbps, BW=95.3kHz

-110

-100

-90

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Frequenc Offset (kHz)

Sen

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)

AFCON

AFCOFF

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Rev. 0.3 7

4. TX Measurements

All TX Measurements unless otherwise specified are measured with VDD = 3.3 V, txpow[2:0]=111, frequency =913 MHz, using the scripts available on the Silicon Labs website and a 4432-DKDB1 test card. All measurementsare done at the output of the lowpass filter at the TX SMA connector. The output power is ~1 dB higher at the TXpin of the chip before the lowpass filter.

4.1. Output Power and Spectrum

Figure 9. Output Power

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8 Rev. 0.3

4.2. Modulated Spectrum

Figure 10. Modulated Spectrum—40 kbps/20 kHz Dev

4.3. TX Deviation

Figure 11. TX Modulation vs. Time—40 kbps/20 kHz Dev

Page 9: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

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Rev. 0.3 9

4.4. TX Output Power Variation vs. VDD and Temperature

Figure 12. TX Output Power vs. Temperature

Figure 13. TX Output Power vs. VDD

TX Output Power vs Temp

18

18.2

18.4

18.6

18.8

19

19.2

19.4

-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

Temp (C)

Ou

tpu

t P

ow

er

TX Output Power vs. VDD

10

12

14

16

18

20

1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6

VDD Voltage

Ou

tpu

t P

ow

er (

dB

m)

Page 10: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

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10 Rev. 0.3

Figure 14. TX Output Power vs. Step (txpower[2:0])

4.5. Conducted Harmonics

Figure 15. Conducted Harmonics

TX Output Power vs Power Step

-5

0

5

10

15

20

0 1 2 3 4 5 6 7

Power Step (txpow[2:0])

TX

Ou

tpu

t P

ow

er (

dB

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Page 11: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

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Rev. 0.3 11

5. FCC Compliance

Silicon Labs has tested the Si4432B chip and 4432-DKDB1 TX/RX Split TRX Test Card for FCC Part 15.247compliance in the 902–928 MHz frequency band, at an output power level of +20 dBm. These FCC compliancetests were performed by Elliott Labs, a FCC certified Electromagnetic Compatibility (EMC) test house. Per FCCPart 15.35, the radiated level of harmonic emissions at frequencies above 1000 MHz are to be measured using anaverage detector function, and thus there may be some advantage in using a burst-like packet structure rather thancontinuous transmission. FCC Part 15.35(c) states that if the packet length is less than 100 ms then time averagingcan be applied which effectively relaxes the harmonic limits. If the packet structure is longer than 100 ms then timeaveraging cannot be used. The following test report is for a continuous-wave tone to test to the more stringent caseof when a packet is longer than 100 ms. Explicit excerpt from FCC 15.35(c):

(c) Unless otherwise specified, e.g.§ 15.255(b), when the radiated emission limits are expressed in terms of theaverage value of the emission, and pulsed operation is employed, the measurement field strength shall bedetermined by averaging over one complete pulse train, including blanking intervals, as long as the pulse traindoes not exceed 0.1 seconds. As an alternative (provided the transmitter operates for longer than 0.1 seconds) orin cases where the pulse train exceeds 0.1 seconds, the measured field strength shall be determined from theaverage absolute voltage during a 0.1 second interval during which the field strength is at its maximum value.

Page 12: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

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12 Rev. 0.3

6. EMC Test Data

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Page 13: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

AN437

Rev. 0.3 13

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�$% �;μ=7* )7� 6�*�� ������ �G7H�7D)� ������� *������0�"2"�/ ��23 = "�2/ '?�2? �I ?�0 �2� �;��$%J=;���$%�0�"2""/ ��2� = 3�2/ '��2� D=K ?�0 �2� �;��$%J=;��/$%�0�"2""/ #02� $ "�2/ '?#2� �I ?#3 �2/ �;��$%J=;���$%�0�"2""/ #02/ $ 3�2/ '��2/ D=K ?#3 �2/ �;��$%J=;��/$%�3��2"�/ �"2/ = 3�2/ '�#2/ �I �/ �2� �;��$%J=;���$%�3��2"�/ ��2# = #�2/ '32# D=K �/ �2� �;��$%J=;��/$%�3��20�/ ��2� $ 3�2/ '�32� �I 0" �2� �;��$%J=;���$%�3�#2/�/ ��2� $ #�2/ '��20 D=K 0" �2� �;��$%J=;��/$%?�#"2"?/ �"2� = 3�2/ '��2� �I ?�� �23 �;��$%J=;���$%?��/2/�/ ��20 = #�2/ '32� D=K ?�� �23 �;��$%J=;��/$%?��/2/�/ ��2� $ #�2/ '32" D=K ��" �20 �;��$%J=;��/$%?��/2/3/ �"2# $ 3�2/ '��2# �I ��" �20 �;��$%J=;���$%�#3#2/0/ �02# = 3�2/ '�#2# �I ��/ �2� �;��$%J=;���$%�#3#2/�/ ��2� = #�2/ '"2� D=K ��/ �2� �;��$%J=;��/$%�#3�2"// �#2# $ 3�2/ '�02# �I ��� �2? �;��$%J=;���$%�#3#2/#/ ?32� $ #�2/ '��2� D=K ��� �2? �;��$%J=;��/$%#�0"20�/ �"23 = 3�2/ '��2? �I ?�� �2� �;��$%J=;���$%#�"/2/// �#2" = #�2/ '02� D=K ?�� �2� �;��$%J=;��/$%#�"/2/// �32� $ 3�2/ '��20 �I ?�0 �2# �;��$%J=;���$%#�0"2"3/ ��20 $ #�2/ '��2� D=K ?�0 �2# �;��$%J=;��/$%��/�2"0/ #�2/ = "�2/ '�?2/ �I �/� �2� �;��$%J=;���$%��/#2/// �32� = 3�2/ '��2� D=K �/� �2� �;��$%J=;��/$%��/#2��/ �02� $ "�2/ '�#2" �I ��� �2� �;��$%J=;���$%��/�2""/ ��2" $ 3�2/ '?�2� D=K ��� �2� �;��$%J=;��/$%3?�/2?�/ #/2/ = 3�2/ '��2/ �I �? �2? �;��$%J=;���$%3?�"2"0/ �/2" = #�2/ '�?2� D=K �? �2? �;��$%J=;��/$%3?�"20"/ �"2� $ 3�2/ '��2� �I ?�0 �2? �;��$%J=;���$%3?�"2"�/ �/2? $ #�2/ '�?23 D=K ?�0 �2? �;��$%J=;��/$%0�?#2/0/ ##2� = 3�2/ '�02� �I ��� �2� �;��$%J=;���$%0�?�2"0/ #�2# = #�2/ '�2# D=K ��� �2� �;��$%J=;��/$%0�?�2"�/ �"2� $ 3�2/ '��2" �I ��? �2/ �;��$%J=;���$%0�?#2/// ?"2� $ #�2/ '��2� D=K ��? �2/ �;��$%J=;��/$%"��"2"�/ �02/ = 3�2/ '��2/ �I 0" �2� �;��$%J=;���$%"�#/2��/ ?32� = #�2/ '��20 D=K 0" �2� �;��$%J=;��/$%"��"2"�/ �02� $ 3�2/ '�#2� �I �"3 �2/ �;��$%J=;���$%"��"2"�/ ?02� $ #�2/ '�#2" D=K �"3 �2/ �;��$%J=;��/$%

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14 Rev. 0.3

DOCUMENT CHANGE LIST

Revision 0.1 to Revision 0.2 Added Section 6 with measured EMC test data.

Revision 0.2 to Revision 0.3 Clarified aspects of FCC certification.

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Rev. 0.3 15

NOTES:

Page 16: ERFORMANCE FCC C OMPLIANCE EST ESULTS 1. Introduction902–928 MHz. The measurement results include receiver sensitivity, adjacent channel selectivity, blocking, transmit output power,

DisclaimerSilicon Laboratories intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers using or intending to use the Silicon Laboratories products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and "Typical" parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Laboratories reserves the right to make changes without further notice and limitation to product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or completeness of the included information. Silicon Laboratories shall have no liability for the consequences of use of the information supplied herein. This document does not imply or express copyright licenses granted hereunder to design or fabricate any integrated circuits. The products must not be used within any Life Support System without the specific written consent of Silicon Laboratories. A "Life Support System" is any product or system intended to support or sustain life and/or health, which, if it fails, can be reasonably expected to result in significant personal injury or death. Silicon Laboratories products are generally not intended for military applications. Silicon Laboratories products shall under no circumstances be used in weapons of mass destruction including (but not limited to) nuclear, biological or chemical weapons, or missiles capable of delivering such weapons.

Trademark InformationSilicon Laboratories Inc., Silicon Laboratories, Silicon Labs, SiLabs and the Silicon Labs logo, CMEMS®, EFM, EFM32, EFR, Energy Micro, Energy Micro logo and combinations thereof, "the world’s most energy friendly microcontrollers", Ember®, EZLink®, EZMac®, EZRadio®, EZRadioPRO®, DSPLL®, ISOmodem ®, Precision32®, ProSLIC®, SiPHY®, USBXpress® and others are trademarks or registered trademarks of Silicon Laboratories Inc. ARM, CORTEX, Cortex-M3 and THUMB are trademarks or registered trademarks of ARM Holdings. Keil is a registered trademark of ARM Limited. All other products or brand names mentioned herein are trademarks of their respective holders.

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