View
4
Download
0
Category
Preview:
Citation preview
PacketMicro, Inc.2312 Walsh Avenue, Suite A, Santa Clara, CA 95051www.packetmicro.com
Power Integrity MeasurementWith
Rohde & Schwarz ZNL VNA
2
Outline
• Typical PDN Impedance Profile Page 3
• Low-Impedance Probing Tips Page 4 - 5
• 2-Port VNA Measurements of ZDUT Page 2 - 9
• Probe-Tip Calibration Page 10
• RProbe & µProbe Comparison Page 11 - 13
• RProbe Specifications Page 14 - 16
• Tools: Probes, Positioners, and Microscopes Page 17 - 20
• Probe Planarization with Mylar Page 22 - 26
• PI Probing in a Box Page 27
• Import TCS70xx.calkit file Page 28 - 30
• Probe-tip SOLT Calibration Page 31 - 44www.packetmicro.com
Typical PDN Impedance Profile
• Impedance profile formed by the interaction of various PDN components
• Impedance peak at package/chip resonance
• Peak impedance dependent on package, PCB, and on-chip parameters
• Typical impedance in the range of tens of milliohms
Board CapsPackage
On-chip DecapsPCB Board
VRM
www.packetmicro.com
4
Low-Impedance Probing Tips
• Keep the length of the test probes or cables as short as possible (1” probe for <300 MHz, VNA calibrated at the cable connectors)
• Minimize the measurement errors at frequency < 10 kHz, which are caused by the ground loop of the two probes
• Minimize the measurement errors at frequency > 10 MHz, which are caused by the mutual coupling between probe current loops.
• Use probe-tip calibration to remove the errors caused by the test probes for high-frequency (>300 MHz) measurements
www.packetmicro.com
5
Low-Freq Errors Caused by Ground Loop
If the DUT’s impedance is very small (ZDUT < tens of milliohms)
Source current flows into source-to-receiver cable GND loop.
Measurement errors occur at LF range (<10kHz)
www.packetmicro.com
6
2-Port VNA Measurements of Low ZDUT
www.packetmicro.com
• 2nd order Analysis
VNA
Port 1 drives the current
~ ~
Port 2 measures the voltage
ZDUT
Port 1 Port 2
(ZDUT<<Zo)
𝑍𝐷𝑈𝑇 = 25𝑆21
1 − 𝑆21𝑍𝐷𝑈𝑇 = 25 S21 Ω
• 1st order Analysis
Ω
7
Minimize I-Loop Coupling: 2-Sided Probing
• 2-sided probing can reduce the errors caused by the coupling of the two probe current loops.
www.packetmicro.com
PacketMicro Vertical Probing Solution (SProbe, TCS70 Cal substrate, FP160 positioner,
and VPH100 PCB holder)http://packetmicro.com/Applications/vertical-probing.html
FP160FP160VPH100
Minimize I-Loop Coupling: 1-Sided Probing
• Minimize the pin length and diameter of the probe to reduce coupling between two probe current loops
• Lay down probes as mush as possible to make the two current loops as far as possible
• If possible, place probes at two close-by pads. However, the distance (L) between the two pads must be sufficiently shorter than the wave length of the max test frequency.
L
8www.packetmicro.com
9
1-Sided Probing cont.
• Proper selection of probes and test pads are important to reduce the current-loop errors
www.packetmicro.com
PacketMicro Horizontal Probing Solution
(RProbe, TCS70 Cal substrate, TP250 positioner, and PH100 PCB holder)
http://packetmicro.com/Products/rf-probe.html
10
Probe-Tip Calculation for Freq > 300 MHz
• Probe-tip calibration removes the errors caused by the probe impedance at high frequency (> 300 MHz)
• Rugged RProbe calibrated with TCS70 has the same performance as the fragile microprobe with calibration
www.packetmicro.com
TCS70 Cal Substrate
Rugged RProbe
PDN Impedance using R-Probes
11
- Device powered off- Device powered on
www.packetmicro.com
3 milliohms
PDN Measurement with ZNL VNA
www.packetmicro.com 12
13
22-Layer Stratix III Test Board
www.packetmicro.com
Bareboard0.9 V Core 34.56 A Max
22-layer Stratix III board PDN Impedance Requirement
PI Probing Demo
• Measure impedance of 0.9 V core voltage
• Probe on C639 and C644
14www.packetmicro.com
PI Probing Demo
C639 and C644 are on the back of the board
15www.packetmicro.com
16
RProbe & Microprobe for Power Integrity
www.packetmicro.com
Strong RProbe has the Microprobe accuracy!
Microprobe
- RProbe- MicroprobeRugged RProbe
17
Impedance Between Bare and Populated Boards
www.packetmicro.com
- Bare Board- Populated Board
R-ProbeFeatures• High Bandwidth: DC to 12 GHz• Low Insertion Loss: < 3 dB @ 15 GHz• Ruggedness: Beryllium Copper tips• Probe-tip Calibration: TCS 70 Cal Substrate• High Repeatability: No moving part
R-Probe Part No.• RP-GR-151504 – 15 GHz, 0.4 mm/16 mil pitch• RP-GR-151505 – 15 GHz, 0.5 mm/20 mil pitch• RP-GR-121508 – 12 GHz, 0.8 mm/32 mil pitch • RP-GR-121510 – 12 GHz, 1.0 mm/40 mil pitch
Un-calibrated S21 for 3 probe pitches Un-calibrated S11 for 3 probe pitches
www.packetmicro.com 18
dB
GHz
dB
GHz
0.5 mm0.8 mm1.0 mm
0.5 mm0.8 mm1.0 mm
Thru Measurement with Probe-Tip Calibration
Calibrated at SMA connector
Calibrated atprobe tips
Thru Measurement
Calibrated at probe tips
Calibrated at SMA connectors
(20 GHz)
(20 GHz)
(20 GHz)
(20 GHz)
Probe-tip calibration (0.5 mm S-Probe)
www.packetmicro.com 19
S11 Measurements of a 50Ω Load
Probe-tip calibration allows accurate, repetitive measurements.
Calibrated at SMA connectors
Calibrated at probe tips(0.5 mm S-Probe)
(20 GHz)
www.packetmicro.com 20
21
Tools - Accessories
Optical Microscope(~ 90 x magnification)
TCS70CalibrationSubstrate
MylarTape
USB Digital Microscope(~ 90 x magnification)(Make sure to use a long working range (5 cm @ 90x) microscope!)
• Using a good microscope is essential.
• You might damage the probe if you cannot see the probe tips well.
www.packetmicro.com
Precision Positioner – TP250
▪ Precise: XYZ stage (100 TPI, 2.5 μm resolution)
▪ Versatile: detachable θ stage
▪ Easy: lockable magnetic base22
Flex Positioner – FP160
XYZ stage
ControlKnob
ProbeHolder
HolderScrew
MagneticBase
PlanarizationKnob
HolderTilt Screw
▪ Flexible: one knob for length and orientation control
▪ Precise: independent XYZ stage (100 TPI)
▪ Versatile: single probe holder for scope, RF, TDR probes
▪ Easy: one knob for probe planarization control
▪ Innovative: US Patent 8,836,357
23www.packetmicro.com
Easy Positioner – TP150
CoarseZ adjustment
Z Control
X Control
Y Control
θ ControlMagnetic Base
▪ Precise: XYZ stage (100 TPI)
▪ Versatile: Easy height adjustment
▪ Easy: magnetic with anti-static rubber base
▪ Video demo: http://www.youtube.com/watch?v=ss9pnBqxmyw
ProbeMount
24www.packetmicro.com
Vertical PCB Holder (VPH100)
25www.packetmicro.comVideo Demo: http://www.youtube.com/watch?v=vNdP1UgcsgM
Quick Release
Handle
Top Handle
Adjustment
Screw
Upper Movable Bar
Lower Movable Bar
Magnetic Base
H: 40 cm/
15.8”
W: 40 cm /15.8”
12.5 cm/
5”
9 cm
1 cm/hole
Min: 4.6 cm/1.8”
Max: 25.4 cm/10”
VPH100-10
VPH100-10 (for PCB height up to 10”)
VPH100-18 (for PCB height up to 18”)
Probing Test Pads on Even Surfaces
• Use the Mylar tape on the back of the plastic cap for probe planarization by observing the indentation caused by the tips.
• Remove the plastic cap and perform probing• Affix a Mylar tape next to test pads if there is not
enough space for placing the plastic cap.
MylarMylar indentation caused by both tips
GND
Signal
www.packetmicro.com 26
Signal tip touches down first
Step 1:
Land the probe tips on the tape and observe the probe-tip footprint. Above image shows that signal tip touches the surface first.
GNDSignal
Mylar indentation caused by signal tip
www.packetmicro.com 27
GND tip touches down first
Step 2:
Adjust the planarization knob on the TP150 positioner to lower the GND tip. Above image shows that GND tip touches the surface first.
Mylar indentation caused by GND tip
GNDSignal
www.packetmicro.com 28
Both tips touch down simultaneously
Step 3:
Adjust the planarization knob on the positioner to land both probe tips. Above image shows the two probe tips touch the surface evenly.
Mylar indentation caused by both tips
GNDSignal
www.packetmicro.com 29
TCS70 on Plastic Carrier
• Use the Mylar tape on the back of the plastic cap for probe planarization
• Place TCS70 on top the plastic cap and perform SOLT calibration
• Remove the TCS70 and start probing
www.packetmicro.com 30
Use Mylar for Probe Planarization
Use TCS70 for SOLT Calibration
Two-Port Probe-Tip Calibration
• Import TCS70 coefficients (probe dependent) into VNA(TCS70_0.5MM.calkit, TCS70_0.8MM.calkit, TCS70_1.0MM.calkit)
• Perform 2-port SOLT calibration
www.packetmicro.com 31
Import TCS70xx.calkit file
www.packetmicro.com 32
Press hard “Cal” button -> Cal Devices -> Cal Kits -> Import Cal Kit
Import TCS70xx.calkit file – cont.
www.packetmicro.com 33
“User Conn 1” connector type and “User Conn 1 Ideal Kit” are generated in addition to the TCS70_x.xmm cal kits.
2-Port Calibration with TCS70
• Reflection calibration (Short, Open, Load calibration for two ports)
• Transmission calibration (Thru calibration)
Thru
G SGS
OpenShort
www.packetmicro.com 34
Start Manual Calibration
www.packetmicro.com 35
Press hard “Cal” button -> Start Cal -> Start (Manual)
Select Cal Kit
Select “User Connect 1” connector -> “Cal Kit” ->Start
www.packetmicro.com 36
Set Marker to Lowest Frequency
Use 180° change in phase to detect short.
www.packetmicro.com 37
Reflection Calibration - Short
Short Pattern
• Perform Short first to verify probe planarization
180° phase change
www.packetmicro.com 38
Reflection Calibration - Open
Open Pattern
Open
www.packetmicro.com 39
Reflection Calibration - Load
Load Pattern
Load
www.packetmicro.com 40
Perform Reflection OSM Cal for Port#2
www.packetmicro.com 41
Transmission Calibration - Thru
• Make sure that both probes touch down
www.packetmicro.com 42
GND SIG
Thru standard on TCS70
Two probes measure the Thru standard.
Transmission Calibration - Thru
• At least one probe does not touch down.
www.packetmicro.com 43
At least one probe does not touch down
Transmission Calibration - Thru
• Both probes touch down
www.packetmicro.com 44
Both probes touch down
Both probes touch down
Correct Thru Calibration
www.packetmicro.com 45
S21 should be flat
Completion of SOLT Calibration
www.packetmicro.com 46
0 dB10 dB/Div
0 dB10 dB/Div
0 dB0.01 dB/Div
0 dB0.01 dB/Div
S11 Measurements of a 50Ω Standard
www.packetmicro.com 47
0 dB
10 dB/Div
S11 after probe tip calibration
References
• Istvan Novak, “Power Integrity: Advanced Design and Characterization” (http://www.cei.se/media/48264/cei%20europe%20course%2056.pdf)
• Istvan Novak, “Measuring Milliohms and Pico Henrys in Power Distribution Networks”
(http://electrical-integrity.com/Paper_download_files/DC00_MeasuringMiliohms_slides.pdf)
• Istvan Novak, “PDN Measurements: Reducing Cable-Braid Loop Error”
(http://www.electrical-integrity.com/Quietpower_files/Quietpower-3.pdf)
www.packetmicro.com 48
49
Thank You
Contact:
support@packetmicro.com Office: 408-675-3900
Power Integrity Probing with Ease!
▪ Rugged RF probes up to 40 GHz
▪ Probe-tip calibration with TCS70 substrate
▪ Precision TP250 and FP160 Positioners (XYZθ)▪ Don’t forget to use Mylar tape for planarization
www.packetmicro.com
Recommended