rf probing - packetmicro inc. · 2018-03-12 · tp150 tp150 fp40 ph100 am4115ztl 24. 2-port...

PacketMicro, Inc.2312 Walsh Avenue, Suite A, Santa Clara, CA 95051 www.packetmicro.com

RF ProbingWith

Keysight E5071C VNA

Outline

• RF Probing Examples Page 3 – 7

• S-Probe Overview Page 8 - 11

• RF Probing Tips Page 12

• Tools: Probes, Positioners,

and Microscopes Page 13 - 15

• Probe Planarization with Mylar Page 16 - 20

• Probing DUT on Uneven Surfaces 1 - 23

• RF Probing in a Box Page 24

• Import TCS60xx.CKX file Page 25 - 28

• SOLT Calibration Page 29 - 38

• Manual Entry of TCS60 into VNA Page 39 - 42

www.packetmicro.com 2

Why RF Probing?

• Necessity: Constant shrinking size of circuit

components makes soldering semi-rigid RF cables to test gigahertz circuits impractical.

• Accuracy: RF probes and calibration substrates

allow engineers to perform probe-tip calibration for accurate, repetitive measurements.

• Productivity: Any engineer can do RF

measurements in minutes without being a master in soldering semi-rigid cable


Measurements of RF Low-Pass Filter

RF probe is almost as good as SMA connector!

SMA-SMA

S-Probe - SMA

Soldered Cable - SMA


RF Fixture Testing

5www.packetmicro.com

S21

-1.31 dB @2.41GHz

RF Module Testing


RF Antenna Testing


S-ProbeFeatures• High Bandwidth: DC to 20 GHz• Low Insertion Loss: < 3 dB @ 20 GHz• Ruggedness: Beryllium Copper tips• Probe-tip Calibration: TCS 60 Cal Substrate• High Repeatability: No moving part

S-Probe Part No.• SP-GR-2015025 – 20 GHz, 0.25 mm/10 mil pitch• SP-GR-201504 – 20 GHz, 0.4 mm/16 mil pitch• SP-GR-201505 – 20 GHz, 0.5 mm/20 mil pitch• SP-GR-181508 – 18 GHz, 0.8 mm/32 mil pitch • SP-GR-181510 – 18 GHz, 1.0 mm/40 mil pitch• SP-GR-161512 – 16 GHz, 1.2 mm/48 mil pitch

Un-calibrated S21 for 3 probe pitches Un-calibrated S11 for 3 probe pitches


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)


2-Port Probe-Tip Calibration Setup

Precision TP300 Positioners with S-Probes


Probe Planarization Tips

• Good contact of both probe tips with the DUT is essential to accurate calibration and measurements.

• Mylar tape provides leveling guidance on flat, even surface (bare PCB).

• Color marker helps on uneven surface (solder bump).• A good microscope is important. You might damage

the probe if you cannot see its tips well.

Tip skid marks

Mylar indentation caused by both tips

GND

Signal


Tools - Accessories

Optical Microscope(~ 90 x magnification)

TCS60CalibrationSubstrate

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 its tips well.

Fine-tipSharpie pen


Precision Positioner – TP250

▪ Precise: XYZ stage (100 TPI, 2.5 μm resolution)

▪ Versatile: detachable θ stage

▪ Easy: lockable magnetic base14

TP150 Precision Positioners (XYZθ)

(Planarization knob)

• Accurate (100 TPI)• Coarse and fine adjustment

without tool


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


Use VNA to Verify Probe Contacts

Both tips touching• Both tips leave light

probe marks• VNA Smith Chart

shows “Short”

Short


Probing Test Pads on Uneven Surfaces

• Color solder bumps with a Sharpie• Use the probe skid marks to confirm good tip

contact• Clean up the solder bumps with industrial alcohol

after probing

Tip

sk

id m

ark

s

Fine-tipSharpie


Use Probe Skid Marks on Solder Bumps

GND Tip Mark

Left GND tip touches down first

Signal Tip Mark

Right signal tip touches down first


Both Tips Touch Down Simultaneously

2 Tip Marks

Both tips touch down simultaneously

Clean up solder bumps with industrial alcohol after probing


RF Probing in a Box

“RF Probing in a Box” ▪ 2x TP150 positioners ▪ 1x FP40 positioner▪ 4x PH100 PCB holders

▪ 1x AM4115ZTL Dino-Lite microscope▪ 2x SP-GR-xx15yy Probes ▪ 1x TCS70 Cal substrate

TP150 TP150

FP40

PH100

AM4115ZTL


2-Port Probe-Tip Calibration

• Import TCS60 coefficients (probe dependent) into VNA(TCS60_05MM.ckx, TCS60_08MM.ckx, TCS60_10MM.ckx)

• Perform 2-port SOLT calibration


Import TCS70xx.CKX file

Press CAL button and choose an unused “User” kit ->


Import TCS60 TCS60xx.CKX file - Cont.

Press “Import Cal Kit” soft key ->


2-Port Calibration with TCS70

• Reflection calibration (Short, Open, Load calibration for two ports)

• Transmission calibration (Thru calibration)

Thru

G SGS

OpenShort


Reflection Calibration - Short

• Perform Short first to verify probe planarization

Short


Reflection Calibration - Open

Open Pattern Open


Reflection Calibration - Load

Load Pattern

Load


Transmission Calibration - Thru

• Make sure that both probes touch down

GND SIG

Thru standard on TCS60Two probes measure the Thru standard.


Transmission Calibration - Thru

• Make sure that both probes touch down

At least one probe does not touch down

Both probes touch down


Correct Thru Calibration


Incorrect Thru Calibration

E5071 Screen ShotDuring Calibration

S21 & S12 < -12 dB

S11 & S22 > -8 dB


Completion of SOLT Calibration

• S11 and S22 should be only a dot on the Smith chart

• S21 and S12 should be a flat line


Completion of SOLT Calibration – cont.

Completion of a good SOLT calibration


Appendix – Manual entry of TCS60

You can manually enter the coefficients of TCS60 Cal Kit by following these steps:


Enter SOLT – cont.


Specify CLS - Short


Specify CLS – Open, Load, Thru


Thank You

Contact:[email protected] Office: 408-675-3900

We help make your high-speed probing

projects successful !• Flex Probe Stations

• Rugged 20 GHz RF Probes

• Laboratory Rental

• Engineering Services

• Signal Integrity Consulting


rf probing - packetmicro inc. · 2018-03-12 · tp150 tp150 fp40 ph100 am4115ztl 24. 2-port...

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