Power Integrity Measurement - PacketMicro Inc.€¦ · 2 Outline •Typical PDN Impedance Profile...

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 - 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

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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

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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)

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6

2-Port VNA Measurements of Low ZDUT

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• 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.

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PacketMicro Vertical Probing Solution (SProbe, TCS70 Cal substrate, FP160 positioner,

and VPH100 PCB holder)http://packetmicro.com/Applications/vertical-probing.html

FP160FP160VPH100

http://packetmicro.com/Applications/vertical-probing.html

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

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PacketMicro Horizontal Probing Solution

(RProbe, TCS70 Cal substrate, TP250 positioner, and PH100 PCB holder)

http://packetmicro.com/Products/rf-probe.html

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

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TCS70 Cal Substrate

Rugged RProbe

PDN Impedance using R-Probes

11

- Device powered off- Device powered on

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3 milliohms

PDN Measurement with ZNL VNA

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13

22-Layer Stratix III Test Board

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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


PI Probing Demo

C639 and C644 are on the back of the board


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RProbe & Microprobe for Power Integrity

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Strong RProbe has the Microprobe accuracy!

Microprobe

- RProbe- MicroprobeRugged RProbe

17

Impedance Between Bare and Populated Boards

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- 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


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)


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)


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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.

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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


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


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


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


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


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


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


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


Import TCS70xx.calkit file


Press hard “Cal” button -> Cal Devices -> Cal Kits -> Import Cal Kit

Import TCS70xx.calkit file – cont.


“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


Start Manual Calibration


Press hard “Cal” button -> Start Cal -> Start (Manual)

Select Cal Kit

Select “User Connect 1” connector -> “Cal Kit” ->Start


Set Marker to Lowest Frequency

Use 180° change in phase to detect short.


Reflection Calibration - Short

Short Pattern

• Perform Short first to verify probe planarization

180° phase change


Reflection Calibration - Open

Open Pattern

Open


Reflection Calibration - Load

Load Pattern

Load


Perform Reflection OSM Cal for Port#2


Transmission Calibration - Thru

• Make sure that both probes touch down


GND SIG

Thru standard on TCS70

Two probes measure the Thru standard.


• At least one probe does not touch down.


At least one probe does not touch down


• Both probes touch down


Both probes touch down

Both probes touch down

Correct Thru Calibration


S21 should be flat

Completion of SOLT Calibration


0 dB10 dB/Div

0 dB10 dB/Div

0 dB0.01 dB/Div

0 dB0.01 dB/Div

S11 Measurements of a 50Ω Standard


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)


http://www.cei.se/media/48264/cei%20europe%20course%2056.pdf

http://electrical-integrity.com/Paper_download_files/DC00_MeasuringMiliohms_slides.pdf

http://www.electrical-integrity.com/Quietpower_files/Quietpower-3.pdf

49

Thank You

Contact:

[email protected] 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

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Power Integrity Measurement - PacketMicro Inc.€¦ · 2 Outline •Typical PDN Impedance Profile...

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Transcript of Power Integrity Measurement - PacketMicro Inc.€¦ · 2 Outline •Typical PDN Impedance Profile...