LeCroy SPARQ and Cascade Microtech Probes Using WinCal XE Calibrationscdn.teledynelecroy.com/files/appnotes/lecroy_sparq... · 2011-10-06 · LeCroy SPARQ and Cascade Microtech Probes

Measurements with the APPLICATION NOTE

LeCroy SPARQ and Cascade Microtech Probes

Using WinCal XE Calibrations

LeCroy Corporation and Cascade Microtech

1

Introduction Measurements on two printed circuit

boards (PCB) were taken using probing

solutions from Cascade Microtech and

network analysis solutions from LeCroy.

The goal was to determine the quality of

measurements taken on a LeCroy SPARQ

4004E Signal Integrity Network Analyzer,

and to determine the compatibility with

Cascade Microtech probes. Two model

ACP40-D-GSSG-400 Cascade Microtech

probes were used. The probe’s part

number can be understood as follows:

‘ACP’ specifies an air coplanar probe,

‘40’ means 40 GHz (using 2.92 mm

connectors), ‘D’ means differential

(dual) tips, ‘GSSG’ means that the tips are arranged in a ground-signal-signal-ground geometry, and ‘400’

means that the tips have 400 micron pitch.

The testing was performed using two boards. The first board was the standard demo board utilized with

the SPARQ. This board comes with two adjacent differential coupled traces with 2.92 mm edge

connectors and two differential loss measurement traces. The differential loss measurement traces

were utilized for this exercise. The second board was a test board manufactured by Connected

Community Networks, Inc. (CCN). CCN is a test lab run by Dr. Don DeGroot, formerly of NIST, who

performs test services and works closely with LeCroy.

In order to de-embed the probes, we used two distinctly different methods. The first method utilized a

second-tier calibration of the SPARQ. The second method utilized the SPARQ application’s time domain

gating feature.

Figure 1 – LeCroy SPARQ with Cascade Microtech probe station

2

The second-tier calibrations were performed by first measuring Cascade Microtech impedance standard

substrates (ISSs). These substrates contain calibration standards with models provided by Cascade

Microtech. Two substrates were utilized: the 106-683A, which contains shorts, opens, and loads for GS

and SG probes between 250 and 1250 µm, and the 129-248 GP Thru, which provides thru standards for

GSSG probes for pitches between 300 and 950 µm. The models for the standards are shown later in this

document. After taking calibrated measurements of these standards, error terms were generated for

use in the SPARQ application in two manners. First, models were generated for the calibration

standards, and the standards measurements and models were converted into an error model using the

SPARQ’s internal SOLT calibration algorithms. Second, the measurements were read into WinCal XE™, a

sophisticated piece of software developed and sold by Cascade Microtech, and various calibration

algorithms were applied. All of the available four-port calibrations were utilized, including SOLT, SOLR,

hybrid SOLT-SOLR and LRRM-SOLR.

The results of the measurements utilizing all of the WinCal XE algorithms, the SPARQ internal SOLT

algorithm (specifically comparing to the WinCal XE generated error terms), and the internal time-gating

features of the SPARQ were compared; all of these measurements performed favorably. The remainder

of this document describes the process utilized and documents our results.

Probing System and Measurement Arrangement Figure 1 shows the arrangement of the SPARQ in the probing station. The cables that connect to the

SPARQ are provided with the instrument. In this arrangement, it is advantageous to use right-angle

connectors with the probes. (Only one set was needed, but in retrospect, applying the right-angle

connectors to both probes would have been easier.) The SPARQ is located off to the left and slightly

above the platen. The probe station employs a vacuum table, which holds the board down and in

position. Two positioners are used that are magnetically attached to the platen and that offer x, y, and z

adjustment along with planarity adjustment of the probes.

Planarity Adjustment Before any measurements were taken, each probe was adjusted for planarity. Planarity adjustment was

performed with a contact substrate which is an alumina substrate with a gold top layer. While examining

the probe under the microscope, the probe is landed on substrate and a small amount of over-travel is

dialed-in. Then, the probe is lifted off the substrate and the substrate is examined under the

microscope. Ideally, four identical black lines are seen on the substrate, each corresponding to one of

the four GSSG probe tips. If darker lines are drawn on one side of the probe with corresponding dimmer

lines on the other, the planarity is adjusted and the exercise is repeated until the lines are symmetric.

Interestingly, the dark lines are not caused by the probes scraping gold of the substrate. Instead, the

gold is burnished at the probe touchdown point and the shinier gold reflects the light away from the

microscope causing it to look dark.

3

Board Measurements The four-port measurements of the boards were performed first using the SPARQ. The SPARQ software

includes an interesting feature that saves all of the TDR and TDT traces acquired during a measurement

to a single file. These traces can be played back later and any manner of correction or readjustment of

various features of the measurement can be

changed, and S-parameters recalculated.

This is a degree of flexibility is not found in

any other type of instrument.

The four-port measurements were

performed on:

1. The CCN 4.9 inch differential trace (seen

in Figure 2)

2. The CCN 3 inch differential trace

3. The CCN 100 mil trace

(utilized for rough calibration of the

time gating feature in SPARQ)

4. The LeCroy SPARQ demo board 4 inch

trace (seen in Figure 1)

SPARQ Setup As mentioned in the last section, the SPARQ has the unique capability for recording all of the TDR/T

traces acquired during a measurement for playback at a later time. Therefore, the measurements taken

of the board traces were really taken with the intention of storing the measurement traces after

acquisition, and then to perform the various calibration algorithms after playback. Toward that goal,

measurement characteristics were setup that made sense for examination of the measurements

without the probes de-embedded.

Figure 3 shows the setup utilized. Of key interest are the DUT length mode, which is set to <20 inches,

and the Normal mode sequence control, which specifies that all TDR acquisitions are taken with 10

software averages for both measurement and calibrations. The SPARQ averages 250 waveforms in

hardware, a total of 2500 total averages per acquisition were taken for each trace, which, as shown,

takes about 5 minutes per measurement. Each measurement is performed by first internally calibrating

the SPARQ, which occurs automatically. The SPARQ is configured to de-embed automatically all cables

used in the measurement, which sets the reference plane at the cable ends (i.e. the point where the

probes are connected to the unit). The SPARQ is configured to generate results to 40 GHz, even though

the final measurement is not valid to this frequency. This can be changed later when the calibrations on

the stored TDR traces are performed.

Figure 2 – CCN Board Measurement using a Cascade

Microtech ACP-Dual probe

4

Figure 3 – SPARQ setup for 3 in. CCN Board Measurement

Figure 4 – Port Configuration for differential trace measurements

Raw Board Measurements All of the previously listed board traces were probed, and the TDR/T traces from the measurements

were saved. One SPARQ feature that was heavily employed prior to measuring the S-parameters was the

“live TDR” mode. This feature was indispensible for confirming that the probe was making good contact,

and saved a large amount of time. An example probe touchdown on the boards is shown in Figure 5.

The results for the CCN 3 inch trace is shown in Figure 6. Five sets of measurements are shown. In the

upper left quadrant the differential insertion loss (lime green) and the common-mode insertion loss

(olive green) are shown. The upper right quadrant shows the differential return loss (pink) and the

common-mode return loss (blue).

5

Figure 5 – Probe Touchdown on CCN board (left) and LeCroy demo board (right)

Figure 6 – CCN 3 inch trace raw measurements

The lower left quadrant shows the differential impedance trace (blue) and the common-mode

impedance (red). Cursors are placed on the impedance measurements which show a differential

impedance of about 105 Ohms and a common-mode impedance of 45 Ohms. The lower right quadrant

shows the impedance trace looking into differential port 2. The right side of the screen shows the Smith

chart with the differential match (yellow) and the differential insertion loss (green).

Of particular interest are the effects of the probe. These are most obvious when viewed from the

impedance profile perspective. Figure 7 shows only traces of the differential and common-mode

impedance profiles looking into port 1. Figure 8 shows only the differential and common-mode

impedance looking into port 2. Here we find that at mixed-mode port 1, the probe is about 255 ps long

(including a portion of the tip to board interface) and at mixed-mode port 2 the probe is about 165 ps

long (also including a portion of the tip to board interface).

6

Figure 7 – Differential (blue) and Common-Mode (red) impedance for CCN 3 inch line looking into port 1

Figure 8 – Differential (blue) and Common-Mode (red) impedance for CCN 3 inch line looking into port 2

7

Calibration Measurements In order to perform a second-tier calibration, multiple measurements were taken utilizing two

impedance standard substrates (ISSs) from Cascade Microtech. Figure 9 shows the probes in the

alignment setup on the ISS for the 106-683A substrate for short, open and load for GS and SG probes.

Figure 9 – Cascade probes probing ISS for calibration

Before performing the calibration measurements, the probes are aligned using alignment marks on the

ISS. The key is to arrange the two sets of probes so the tips contact the ISS at a small tick mark offset

from the lines and that as the probes our brought down further, the over-travel slides the tips up to the

edge of the line.

After alignment, the probes were lifted and the open measurement was performed. The open standard

was a measurement with the probes in the air out of contact with the substrate. Then, each GS pair

(single-ended ports 1 and 3) and each SG pair (single-ended ports 2 and 4) were utilized to measure

loads and shorts. Then, a straight thru measurement was performed, followed by a loopback thru

measurement, followed by two diagonal thru measurements.

8

Alignment

Load Measurement

Short Measurement

Dual Straight Thru Measurement

Dual Loopback Thru Measurement

Diagonal Thru Measurement

Figure 10 – Probe calibration measurement arrangements

Pictures of the probe alignment for these measurements are shown in Figure 10. The calibration

measurements are taken with the same settings as shown previously for the board measurements,

except for the following:

9

1. No causality, passivity, or reciprocity enforcements were utilized – the calibration is expected to

correct for any such violations. If desired, these enforcements can be applied to final calibrated

measurements. In general, it is not appropriate to apply enforcements of causality, passivity, or

reciprocity for calibration standards measurements.

2. Since the probe and the standards are very short, the impulse response limiting is set to 1 ns.

Applying this feature causes the SPARQ software to restrict the impulse response (i.e. time

domain response) of any S-parameter to operate over this short range. This generates smoother

measurement results for calibration.

3. All measurements were performed single-ended. This is because the SPARQ second-tier

calibration is always performed on single-ended data prior to any mixed-mode conversion.

These settings are shown in Figure 11. The left-side of the figure shows the extended view of the setup

dialog, with the unchecked settings for the enforcements, and with the impulse response limiting set to

1 ns. On the right-side of the figure, the SPARQ port configuration is shown. The configuration shown is

an example arrangement for a four-port single-ended measurement, but with only the S-parameters for

port 3 saved. This was done strictly for convenience; while we could have taken all measurements as

single-port measurements, all standards measurements were taken as four-port measurements and the

desired result was extracted from the four-port measurement using configurations as shown in Figure

11. Using this approach allows for cross-talk verification. To clarify, for example, for the open standard

measurement, a four-port measurement was performed with the probe out of contact with the

substrate and each one port measurement was generated by configuring the SPARQ port configuration

for the desired measurement result. In this manner, one four-port measurement is taken for each

standard measurement, and the desired results are extracted from this measurement using the port

configuration shown.

Figure 11 – SPARQ single-ended standard measurement (1 port from port 3 of four-port measurement)

10

Second-Tier SOLT Calibration SPARQ has the capability of applying user calibrations as a second-tier calibration. A second-tier

calibration refers to a calibration applied on top of another calibration. Because the standard

measurements performed utilized measurements that were calibrated to the cable ends, error-terms

calculated based on the calibrated standard measurements (in conjunction with the calibration standard

models) serve to mostly de-embed the probes, while also correcting any minor errors in the SPARQ

cable and fixture de-embedding.

Figure 12 – SPARQ calibration dialog showing User Second-tier Calibration capability

Figure 12 shows the SPARQ calibration dialog which includes settings for various calibration controls and

policies. On the lower right of the dialog, a second-tier calibration capability is provided. Second-tier

calibrations are performed in the factory as part of the SPARQ construction and calibration and a factory

second-tier calibration box is shown checked. The user can apply yet another calibration by selecting a

.L12T file format and applying the calibration by checking the User calibration checkbox. The .L12T file is

a LeCroy format, and includes error-terms used internally by the SPARQ software. The SPARQ has the

capability of converting several types of error-term formats into the LeCroy format for subsequent

application to the measurement. The two error-term formats that are interesting for the purposes of

this paper the SOLT conversion and the WinCal XES1P conversion which will be described later.

When the Convert button is pressed, another dialog opens requesting information on how to perform

the conversion. Here, four ports are selected with 8000 points to 40 GHz. In general, a SPARQ prefers

these values, although it will always automatically resample data if provided in alternate forms. There is

no implication here that the calibration is truly valid to this frequency, but using this configuration

provides the most flexibility.

In the figure, the conversion type is set to SOLT and an output file selected for the result. The key here is

the output file directory, where it is expected to find various information required by SPARQ to generate

the error-terms.

SOLT Second-Tier Calibration Directory Information

The directory where the output .L12T file is to be placed contains the following information before and

after the calibration conversion:

11

Before Conversion:

Standards

o Load.s1p –definition of the load standard

o Open.s1p – definition of the open standard

o Short.s1p – definition of the short standard

o Thru12.s2p, Thru34.s2p – definition of the loopback thru standard

o Thru13.s2p, Thru24.s2p – definition of the straight thru standard

o Thru14.s2p, Thru23.s2p – definition of the diagonal thru standard

Standards Measurements

o LM1.s1p, LM2.s1p, LM3.s1p, LM4.s1p – load standard measurements

o SM1.s1p, SM2.s1p, SM3.s1p, SM4.s1p – short standard measurements

o OM1.s1p, OM2.s1p, OM3.s1p, oM4.s1p – open standard measurements

o TM13.s2p, TM24.s2p – dual straight thru standard measurements

o TM12.s2p, TM34.s2p – dual loopback thru standard measurements

o TM14.s2p, TM23.s2p – diagonal thru standard measurements

ConvertSettings.vbs – Additional instructions for the conversion

After Conversion:

ConversionLog.txt – log file showing information on how the conversion proceeded

SecondTier_1.s8p, SecondTier_2.s8p, SecondTier_3.s8p, SecondTier_4.s8p – error-terms in s-

parameter file format for easy viewing

SecondTierCalibration.L12T – second-tier calibration file which can be imported in SPARQ

Standard Definitions

The standard definitions were taken from the ISS and probe data sheets provided by Cascade Microtech,

or directly out of WinCal XE. Specifically:

Load – assumed perfect 50 Ohms

Open – assumed as -7 fF capacitor with no offset length

Short – assumed as 28.8 pH inductor with no offset length

Straight Thru – assumed as 5.7 ps 50 Ohm line with skin-effect loss term

Loopback Thru – assumed as 5.2 ps 50 Ohm line with skin-effect loss term

Diagonal Thru – assumed as 8.1 ps 50 Ohm line with skin-effect loss term

The loss term is provided as:

Reference Delay – 27 ps

Reference Loss - 0.55 dB

Reference Frequency – 40 GHz

12

Such that it follows the following equation:

( ) (

) √

[ 1 ] – equation for loss for thru elements

The models used for the standards definition is provided in Figure 14. These are generated for each

standard and stored in the second-tier calibration directory for conversion.

Convert Settings

When the second-tier calibration is utilized primarily for the purpose of de-embedding, especially for de-

embedding small things, it is helpful to apply some response length limiting to the data for sake of

smoothing. These settings are shown in Figure 13 where 5 ns were utilized.

Figure 13 – ConvertSettings.vbs file used for SOLT conversion

Conversion

Once the conversion settings are entered and it is ensured that all of the standard measurement and

definition files exist in the directory specified for the .L12T file generation, pressing the convert or the

convert or apply button begins the conversion process. The conversion log file shown in Figure 15 shows

how the conversion proceeds. There are many informational messages shown in the log file – if a fatal

error is detected, it would have been logged as such and the final .L12T file would not have been

created.

The conversion is to the so-called 12-term error model which consists of the following types of error-

terms:

mEd - directivity at port m when port m driven

mEs - source match at port m when port m driven

mEr - reverse transmission at port m when port m driven

nmEx - crosstalk at port n due to port m driven (generally not used)

nmEl - load match at port n when port m driven

nmEt - forward transmission at port n when port m driven

The 12-term model when applied to four ports means that the calibration generates 36 terms.

set app = CreateObject("LeCroy.SparqApp.1")

app.SPARQ.ConvertSecondTierCalibration.CausalityImpulseResponseLimitingEnabled = True

app.SPARQ.ConvertSecondTierCalibration.CausalityMaxImpulseLength = 5e-9

13

Short Magnitude

Short Phase

Open Magnitude

Open Phase

Load Magnitude is zero Load Phase is zero

Loopback Thru Magnitude

Loopback Thru Phase

Straight Thru Magnitude

Straight Thru Phase

Diagonal Thru Magnitude

Diagonal Thru Phase

Figure 14 – ISS Standard Models

14

Figure 15 – ConversionLog.txt file output

: <2nd Tier Cal> : Second Tier Calibration Conversion Started: 4 ports, 8000 points, 4.000000e+010 end frequency : <2nd Tier Cal> : File Path Specified: C:\Cascade\SoltSecondTier : <2nd Tier Cal> : Second Tier Calibration is SOLT : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\SM1.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\OM1.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\LM1.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\SM2.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\OM2.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\LM2.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\SM3.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\OM3.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\LM3.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\SM4.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\OM4.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\LM4.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\TM12.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\TM13.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\TM14.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\TM23.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\TM24.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\TM34.s2p was found and read : <2nd Tier Cal> : cable files not used : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Short1.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Short2.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Short3.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Short4.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Short.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Open1.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Open2.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Open3.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Open4.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Open.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Load1.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Load2.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Load3.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Load4.s1p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Load.s1p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru12.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru21.s2p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru13.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru31.s2p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru14.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru41.s2p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru23.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru32.s2p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru24.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru42.s2p not read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru34.s2p was found and read : <2nd Tier Cal> : file: C:\Cascade\SoltSecondTier\Thru43.s2p not read : <2nd Tier Cal> : Second Tier Calibration LeCroy 12-term file: C:\Cascade\SoltSecondTier\SecondTierCalibration.L12T written

15

SecondTier_x.s8p files

After the conversion, four files were created which contain the same error-terms as in the .L12T file, but

in an easily readable form readable by any s-parameter viewing tool. These files are for viewing the

error terms only and are not used by the system.

The format for these files is such that they have the error-terms in an 8 port device model at the

appropriate locations. The eight port device has four ports on the left numbered one through four,

which correspond to the measurement ports. The other four ports on the right numbered five through

eight correspond to the DUT ports. There is one device per left port driven so that the file

SecondTier_1.s8p corresponds to the port 1 driving condition, SecondTier_2.s8p corresponds to the port

2 driving condition and so on.

If we refer to the s-parameters of the file SecondTier_m.s8p as mE , then we have the following s-

parameter formats:

1 1

21 21

31 31

41 41

1

1

21

31

41

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

1 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

Ed Et

Ex Et

Ex Et

Ex Et

Es

El

El

El

E

12 12

2 2

32 32

42 42

2

12

2

32

42

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0

0 1 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

Ex Et

Ed Er

Ex Et

Ex Et

El

Es

El

El

E

13 13

23 23

3 3

43 43

3

13

23

3

43

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 1 0 0 0 0

0 0 0 0 0 0 0

Ex Et

Ex Et

Ed Er

Ex Et

El

El

Es

El

E

14 14

24 24

34 34

4 4

4

14

24

34

4

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 0 0 0 0

0 0 0 1 0 0 0

Ex Et

Ex Et

Ex Et

Ed Er

El

El

El

Es

E

[ 2 ] – Error-term s-parameter file format

16

Error

Term

Term Error

Term

Term Error

Term

Term Error

Term

Term

1Ed 111E 12Ex

122E 13Ex 133E 14Ex

144E

1Es 551E 12El

552E 13El 553E 14El

554E

1Er 151E 12Et

152E 13Et 153E 14Et

154E

21Ex 211E 2Ed

222E 23Ex 233E 24Ex

244E

21El 661E 2Es

662E 23El 663E 24El

664E

21Et 261E 2Er

262E 23Et 263E 24Et

264E

31Ex 311E 32Ex

322E 3Ed 333E 34Ex

344E

31El 771E 32El

772E 3Es 773E 34El

774E

31Et 371E 32Et

372E 3Er 373E 34Et

374E

41Ex 411E 42Ex

422E 43Ex 433E 4Ed

444E

41El 881E 42El

882E 43El 883E 4Es

884E

41Et 481E 42Et

482E 43Et 483E 4Er

484E

Table 1 – Error term locations in second-tier calibration s-parameter files

WinCal XE WinCal XE is a very sophisticated tool provided by Cascade Microtech that performs many advanced

functions including advanced calibration algorithms, direct network analyzer control, probe positioned

control, error analysis and more. In this application note WinCal XE was used only for the calibration of

the SPARQ. Although WinCal XE has many features and looks quite daunting, it is in fact very easy to set

up and the error terms exported from WinCal XE are readily usable in the SPARQ.

When WinCal XE is executed, we have the screen as shown in Figure 16. We will utilize the System and

Calibrate dialog choices. We will start with the System Setup, which configures the probes and probe

orientation along with the calibration substrate selections. Then we will enter calibration measurement

data in the Calibration dialogs and calculate and export error-terms.

17

Figure 16 – WinCal XE main dialog

WinCal XE System Setup

The system setup involves choosing the network analyzer, probes, probe orientation, calibration

substrates and probe positioner.

When System is selected from the dialog in Figure 16, a multi-tab dialog is shown. The first tab shows

the VNA selection: Virtual VNA is selected as shown in Figure 17. Then select the Station tab and select

Manual Station as shown in Figure 18.

Figure 17

Figure 18

Then, the Probes tab is selected and the probe is selected as: ACP base probe, GSSG signal

configuration, wide pitch probe with pitch of 400 um. The probes are selected as dual tip probes and

their port and orientations are selected as shown in Figure 19.

18

Figure 19

Figure 20

One thing to notice in Figure 19 is the port numbering relative to the probe numbering. When specifying

the west probe, VNA port 1 and 2 are specified as a GSSG probe and port 1 is specified with dual probe

signal 1 and port 2 is specified with dual probe signal 2. For the east probe, VNA port 3 is specified with

dual probe signal 2 and port 4 is specified with dual probe signal 1.

The diagram shown by WinCal XE helps in this orientation. It is advantageous to match this orientation

to the SPARQ port orientation, although both WinCal XE and the SPARQ can be operated with port

renumbering employed. The port numbering chosen here means that the default WinCal XE numbering

is utilized which helps to avoid confusion. This default port numbering is shown in Figure 20.

19

Figure 21

Figure 21 shows the substrate selections. The 106-683A substrate is selected, which contains shorts,

opens, and loads for GS and SG probes for between 250 and 1250 um and the 129-248 GP Thru which

provides thru standards for GSSG probes for pitches between 300 and 950 um.

A picture of the 106-683A substrate is shown in Figure 22; the 129-248 substrate is shown in Figure 23.

Note that generally the serial number of the substrate should be entered. This is because some of the

elements in the substrate may not be calibrated and the serial number is required to provide a map

showing the valid calibration standard locations. In our case, we knew the valid locations and opted to

skip this step.

The specification of these substrates is mostly used by automatic positioners to locate the standards. It

also enables WinCal XE to know the model for the standards as outlined previously.

20

Figure 22

Figure 23

WinCal XE Calibration Setup

To begin the calibration setup, we select Calibration from the WinCal XE main dialog, shown in Figure

16. A menu as shown in Figure 24 is displayed. To begin, we select the 4-port SOLT (4-6 Thru) from the

calibration method selection. This is best for the first choice because it requires all of the

measurements. We will only need to load these measurements one time. Select the Second-tier

calibration box since this will be a second-tier calibration applied to the SPARQ. This is important

because unless this box is checked, WinCal XE will require switch-terms for the SPARQ which are

irrelevant for a second-tier calibration.

When the 4-port SOLT (4-6 Thru) calibration method is selected, WinCal XE defaults to using the

loopback thru and straight thru, avoiding the diagonal thrus. Selecting Setup and then Calibration Setup

in the pull-down menu exposes the dialog as shown in Figure 25 where you can see all of the standards

measurements listed for each port. Expanding the thrus shows a checklist of thru connections. Here, the

unchecked Thru (1-4) and Thru (2-3) are selected so that the diagonal thrus are now required.

21

Figure 24

Figure 25

Note that in Figure 25, when the Thru (2-3) is selected, the substrate where the thru is taken from along

with the model of the thru is shown in a window on the right. This model can be verified against the

standards models previously discussed.

Returning to the dialog in Figure 24, the next step is to load each of the standards measurements. Using

the same files with the naming conventions as provided in the section entitled SOLT Second-Tier

Calibration Directory Information, The files are loaded in turn by selecting each measurement, right

clicking, and selecting Load Measurement From File as shown in Figure 26. Once each measurement is

selected, WinCal XE loads the measurement, and the View button is ungrayed – you can then view each

of the files loaded for verification. The ports 2,3 (Thru 2-3) measurement is shown in Figure 27.

The need for reloading the data can be prevented when the calibration method is changed by saving all

of the data. The data is saved by selecting Calibration, then Data from the pull-down, then Save All…, as

shown in Figure 28. The data can be saved anywhere – the user needs to remember where it is saved so

that it can be loaded again later.

Make sure the Second Tier Calibration box is set prior to loading and saving the data, otherwise the

saved data may not be readable and the data will need to be loaded again!

22

Figure 26

Figure 27

Figure 28

Figure 29

23

Calibration Data Generation

After all of the measurements are loaded and the data saved, select Calibration then Error Terms from

the pull-down menu and select Compute. When WinCal XE has finished, select Calibration then Error

Terms from the pull-down menu and select Save. Save these files to a directory where you will want the

LeCroy 12-term error-term calibration file to be generated.

Here we can cycle through the calibrations and generate WinCal XE error-terms data for any calibration

method possible. Here we repeat the calibrations for the following types of calibrations (selected in the

Calibration Methods selection area of the Calibration dialog):

4-Port SOLT (4-6 Thru)

4-Port SOLR (4-6 Thru)

4-Port Hybrid SOLT-SOLR (4 Thru)

4-Port Hybrid LRRM-SOLR (4 Thru)

These selections are shown in Figure 30.

To summarize the procedure for generating the WinCal XE calibrations, do the following once the

measurement data has been loaded once and saved:

1. Select the Calibration Method – when a new calibration method is selected, the measurement

data will be cleared. Ensure that the second-tier calibration box is checked.

2. Select Calibration, then Data from the pull-down, then Load All… and then select the folder

where the measurement data was stored. You will see the measurements available because the

View buttons will be ungrayed.

3. Select Calibration, then Error Terms from the pull-down, then compute – the error terms are

computed.

4. Select Calibration, then Error Terms from the pull-down, then Save… - select the folder where

the LeCroy error-terms calibration file will be placed.

24

Figure 30

Converting WinCal XE Error-Terms in SPARQ Figure 31 shows the SPARQ Calibration dialog configured for WinCal XES1P conversion. The floating

dialog in the middle appears when the Convert… button is pressed. Here, four ports are selected with

8000 points to 40 GHz. As previously described, in general, the SPARQ software prefers these number of

points and end frequency (although it will always automatically resample data if provided in alternate

forms). There is no implication here that the calibration is truly valid to this frequency, but using this

configuration provides the most flexibility.

Here, the conversion type is set to WinCal XES1P and an output file is selected for the result. The key

here is the output file directory, where it is expected to find various information required by SPARQ to

generate the error-terms.

Figure 31 – SPARQ Second-Tier Calibration Conversion Dialog with WinCal XE Selection

25

WinCal XE Second-Tier Calibration Directory Information

The directory where the output .L12T file is to be placed contains the following information before and

after the calibration conversion:

Before Conversion:

WinCal XE Error-terms Files: 36 files output from WinCal XE containing the error-terms

(previously described) with a file naming convention as follows:

Error Term # of Files File Name

mEd 4 ErrorTerm_mm_EDir.s1p

mEs 4 ErrorTerm_mm_ESrm.s1p

mEr 4 ErrorTerm_mm_ERft.s1p

nmEx 12 ErrorTerm_nm_EXtlk.s1p

nmEl 12 ErrorTerm_nm_ELdm.s1p

nmEt 12 ErrorTerm_nm_ETrt.s1p

ConvertSettings.vbs – Additional instructions for the conversion

After Conversion:

ConversionLog.txt – log file showing information on how the conversion proceeded

SecondTier_1.s8p, SecondTier_2.s8p, SecondTier_3.s8p, SecondTier_4.s8p – error-terms in s-

parameter file format for easy viewing (as previously described).

SecondTierCalibration.L12T – second-tier calibration file which can be imported in SPARQ

Note that the conversion directory and its input data is independent of the type of WinCal XE calibration

being performed. In other words, regardless of the calibration method used in generating the error-

terms, the data in the directory is created by WinCal XE and required by SPARQ. Figure 32 shows a

sample log file created for a WinCal XE calibration. Here, you can see that the SPARQ basically reads in

the error-terms in the single-port .s1p files and outputs a single .L12T file containing the calibration.

Time-domain Gating The SPARQ has a unique feature for taking the probe out of the measurements that is a mixture of time-

domain gating and de-embedding. The dialog for this feature, along with the settings used for all of the

time-domain gated measurements, is shown in Figure 33.

26

Figure 32 – ConversionLog.txt file output

Figure 33 – Time-domain Gating Dialog with Cascade Probes Settings

: <2nd Tier Cal> : Second Tier Calibration Conversion Started: 4 ports, 8000 points, 4.000000e+010 end frequency : <2nd Tier Cal> : File Path Specified: C:\WinCal XE 4-port SOLR (4-6 Thru) : <2nd Tier Cal> : Second Tier Calibration is WinCal XES1P : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_11_EDir.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_11_ERft.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_11_ESrm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_12_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_12_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_12_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_13_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_13_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_13_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_14_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_14_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_14_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_21_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_21_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_21_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_22_EDir.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_22_ERft.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_22_ESrm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_23_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_23_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_23_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_24_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_24_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_24_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_31_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_31_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_31_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_32_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_32_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_32_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_33_EDir.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_33_ERft.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_33_ESrm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_34_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_34_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_34_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_41_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_41_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_41_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_42_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_42_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_42_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_43_EXtlk.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_43_ETrt.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_43_ELdm.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_44_EDir.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_44_ERft.s1p was found and read : <2nd Tier Cal> : file: C:\WinCal XE 4-port SOLR (4-6 Thru)\ErrorTerm_44_ESrm.s1p was found and read : <2nd Tier Cal> : Second Tier Calibration files read : <2nd Tier Cal> : Second Tier Calibration LeCroy 12-term file: C:\WinCal XE 4-port SOLR (4-6 Thru)\SecondTierCalibration.L12T written

27

The time gating parameters were taken by placing a cursor at the location of the impedance

discontinuity known to be the probe tip. For the probe with no right-angle connectors, this was

determined to be 165 ps (Cascade Microtech specifies 170 ps) and for the probes with the right angle

connectors, this was determined to be 255 ps. We use 100 mdB per GHz per ns of electrical length which

mostly makes the straight-thru measurements nearly lossless. Impedance peeling is utilized to properly

characterize the probe return-loss and the return-loss effects on the thru response.

Measurement Results The following four sections show screens of the measurement results of four different DUTs using each

of seven different calibration methods. The four DUTs are:

LeCroy Demo Board

CCN 3 inch trace

CCN 4.9 inch trace

Calibration Substrate (ISS) Straight Thru Standard

The calibration methods used are:

None – Raw Measurement

WinCal XE SOLR

WinCal XE SOLT

LeCroy SOLT

WinCal XE Hybrid SOLT-SOLR

WinCal XE Hybrid LRRM-SOLR

LeCroy Time-domain Gating

A description of the setup for each measurement includes:

All measurements are full mixed-mode s-parameters.

Measurements are 201 points from DC to 30 GHz.

All frequency domain measurements are shown to 20 GHz horizontally (centered at 10 GHz at 2

GHz per division) and over 40 dB vertically (centered at -15 dB at 5 dB per division).

All time-domain measurements are shown over 5 ns (centered at 2.5 ns at 500 ps per division).

All impedance plots are shown over 2.5 ns electrical length horizontally (centered at 1.25 ns at

250 ps per division) and 200 Ohms vertically (centered at 100 Ohms at 25 Ohms per division).

No passivity, reciprocity or causality enforcement with impulse response limiting of 5 ns

28

LeCroy Demo Board Trace Measurements

Figure 34 - LeCroy Demo Board – No Calibration for Probe De-embedding

Figure 35 - LeCroy Demo Board – WinCal XE SOLR Calibration

29

LeCroy Demo Board Trace Measurements, continued

Figure 36 – LeCroy Demo Board – WinCal XE SOLT Calibration

Figure 37 - LeCroy Demo Board – LeCroy SOLT Calibration

30


Figure 38 - LeCroy Demo Board – WinCal XE Hybrid SOLT-SOLR Calibration

Figure 39 - LeCroy Demo Board – WinCal XE Hybrid LRRM-SOLR Calibration

31


Figure 40 – LeCroy Demo Board – Time-Domain Gating

32

CCN Three Inch Trace Measurements

Figure 41 - CCN 3 Inch Trace – No Calibration for Probe De-embedding

Figure 42 - CCN 3 Inch Trace – WinCal XE SOLR Calibration

33

CCN Three Inch Trace Measurements, continued

Figure 43 – CCN 3 Inch Trace – WinCal XE SOLT Calibration

Figure 44 – CCN 3 Inch Trace – LeCroy SOLT Calibration

34


Figure 45 - CCN 3 Inch Trace – WinCal XE Hybrid SOLT-SOLR Calibration

Figure 46 - CCN 3 Inch Trace – WinCal XE Hybrid LRRM-SOLR Calibration

35


Figure 47 – CCN 3 Inch Trace – Time-Domain Gating

36

CCN 4.9 Inch Trace

Figure 48 - CCN 4.9 Inch Trace – No Calibration for Probe De-embedding

Figure 49 - CCN 4.9 Inch Trace – WinCal XE SOLR Calibration

37

CCN 4.9 Inch Trace, continued

Figure 50 – CCN 4.9 Inch Trace – WinCal XE SOLT Calibration

Figure 51 – CCN 4.9 Inch Trace – LeCroy SOLT Calibration

38


Figure 52 - CCN 4.9 Inch Trace – WinCal XE Hybrid SOLT-SOLR Calibration

Figure 53 - CCN 4.9 Inch Trace – WinCal XE Hybrid LRRM-SOLR Calibration

39


Figure 54 – CCN 4.9 Inch Trace – Time-Domain Gating

40

CCN 100 Mil Thru

Figure 55 - CCN 100 Mil Thru – No Calibration for Probe De-embedding

Figure 56 - CCN 100 Mil Thru – WinCal XE SOLR Calibration

41

CCN 100 Mil Thru, continued

Figure 57 – CCN 100 Mil Thru – WinCal XE SOLT Calibration

Figure 58 – CCN 100 Mil Thru – LeCroy SOLT Calibration

42


Figure 59 - CCN 100 Mil Thru – WinCal XE Hybrid SOLT-SOLR Calibration

Figure 60 - CCN 100 Mil Thru – WinCal XE Hybrid LRRM-SOLR Calibration

43


Figure 61 – CCN 100 Mil Thru – Time-Domain Gating

44

Cascade ISS Straight Thru Standard

Figure 62 - Cascade ISS Straight Thru Standard – No Calibration for Probe De-embedding

Figure 63 - Cascade ISS Straight Thru Standard – WinCal XE SOLR Calibration

45

Cascade ISS Straight Thru Standard, continued

Figure 64 – Cascade ISS Straight Thru Standard – WinCal XE SOLT Calibration

Figure 65 – Cascade ISS Straight Thru Standard – LeCroy SOLT Calibration

46


Figure 66 - Cascade ISS Straight Thru Standard – WinCal XE Hybrid SOLT-SOLR Calibration

Figure 67 - Cascade ISS Straight Thru Standard – WinCal XE Hybrid LRRM-SOLR Calibration

47


Figure 68 – Cascade ISS Straight Thru Standard – Time-Domain Gating

Measurement Result Comparisons The following four sections show comparisons of four different DUTs using each of six different

calibration methods. The four DUTs are:

LeCroy Demo Board

CCN 3 inch trace

CCN 4.9 inch trace

Calibration Substrate (ISS) Straight Thru Standard

The Calibrations used are:

WinCal XE SOLR

WinCal XE SOLT

LeCroy SOLT

WinCal XE Hybrid SOLT-SOLR

WinCal XE Hybrid LRRM-SOLR


Each section begins with the name of the DUT followed by various parameters measured from the DUT.

The differential and common-mode impedance was measured off the impedance trace with no de-

embedding employed and are estimates. The differential and common-mode delay values are employed

48

to unfold the phase. In other words, for a given measured phase ( )f , a delay value Td is arrived at

such that the following function [ 3 ] mostly flattens out the phase:

( ( ( )))

[ 3 ] – Phase Flattening Function

Then, the value of Td which does this is assumed to be the delay value.

Since most of the lines have extremely different common-mode impedances, the loss at 20 GHz is

measured by first converting the s-parameters to the common-mode impedance and then reading the

loss from the plot.

For time-domain gating, an adjustment was required of 4.5 ps. This is because the values for the gate

was chosen a few picoseconds beyond the probe – this helps with removing tip effects. This tip effect

removal led to better measurements of the actual line, but distorted somewhat the comparison as a

true traditional calibration method.

LeCroy Demo Board

Differential Delay – 520 ps

Common-mode Delay – 595 ps

Differential Impedance – 105 Ohms

Common-mode Impedance – 45 Ohms

Time-domain Gating Adjustment – 4.5 ps

Differential Loss @ 20 GHz – 6 dB

Common-mode Loss @ 20 GHz (in common-mode reference impedance) – 6 dB

49

Figure 69 – LeCroy Demo Board – SD2D1 Magnitude

Figure 70 – LeCroy Demo Board – SD2D1 Phase

Figure 71 – LeCroy Demo Board – SC2C1 Magnitude

Figure 72 – LeCroy Demo Board – SC2C1 Phase

0 5 10 15 2010

8

6

4

2

0

2

4

WinCal SOLT

WinCal SOLR

WinCal Hybrid SOLT -SOLR

WinCal Hybrid LRRM-SOLR

LeCroy SOLT


frequency (GHz)

mag

nit

ud

e (

dB

)

.

0 5 10 15 2040

30

20

10

0

10

20

30

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

ph

ase

(d

eg)

.

0 5 10 15 2010

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6

4

2

0

2

4

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

mag

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dB

)

.

0 5 10 15 20100

80

60

40

20

0

20

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

ph

ase

(d

eg)

.

50

Figure 73 – LeCroy Demo Board – SD1D1 Magnitude

Figure 74 – LeCroy Demo Board – SC1C1 Magnitude

CCN 3 Inch Trace


Common-mode Delay – 475 ps





Common-mode Loss @ 20 GHz (in common-mode reference impedance) – 6.5 dB

0 5 10 15 2050

40

30

20

10

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

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WinCal SOLR



LeCroy SOLT


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.

51

Figure 75 – CCN 3 Inch Trace – SD2D1 Magnitude

Figure 76 – CCN 3 Inch Trace – SD2D1 Phase

Figure 77 – CCN 3 Inch Trace – SC2C1 Magnitude

Figure 78 – CCN 3 Inch Trace – SC2C1 Phase

0 5 10 15 2010

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6

4

2

0

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

mag

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ud

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dB

)

.

0 5 10 15 20100

80

60

40

20

0

20

40

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

ph

ase

(d

eg)

.

0 5 10 15 2010

8

6

4

2

0

2

4

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

magn

itu

de (d

B)

.

0 5 10 15 20200

150

100

50

0

50

100

150

200

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

phase

(d

eg)

.

52

Figure 79 – CCN 3 Inch Trace – SD1D1 Magnitude

Figure 80 – CCN 3 Inch Trace – SC1C1 Magnitude

CCN 4.9 Inch Trace


Common-mode Delay –770 ps






0 5 10 15 2050

40

30

20

10

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

mag

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ud

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dB

)

.

0 5 10 15 2050

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

mag

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.

53

Figure 81 – CCN 4.9 Inch Trace – SD2D1 Magnitude

Figure 82 – CCN 4.9 Inch Trace – SD2D1 Phase

Figure 83 – CCN 4.9 Inch Trace – SC2C1 Magnitude

Figure 84 – CCN 4.9 Inch Trace – SC2C1 Phase

0 5 10 15 2010

8

6

4

2

0

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4

WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

mag

nit

ud

e (

dB

)

.

0 5 10 15 20200

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100

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0

50

WinCal SOLT

WinCal SOLR



LeCroy SOLT


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ph

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(d

eg)

.

0 5 10 15 2015

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


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.

0 5 10 15 20200

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0

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

ph

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(d

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.

54

Figure 85 – CCN 4.9 Inch Trace – SD1D1 Magnitude

Figure 86 – CCN 4.9 Inch Trace – SC1C1 Magnitude

CCN 100 mil Thru



Differential Impedance – (100?) Ohms

Common-mode Impedance – (25?) Ohms




0 5 10 15 2050

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WinCal SOLR



LeCroy SOLT


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LeCroy SOLT


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55

Figure 87 – CCN 100 mil Thru – SD2D1 Magnitude

Figure 88 – CCN 100 mil Thru – SD2D1 Phase

Figure 89 – CCN 100 mil Thru – SC2C1 Magnitude

Figure 90 – CCN 100 mil Thru – SC2C1 Phase

0 5 10 15 20

4

2

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WinCal SOLT

WinCal SOLR



LeCroy SOLT


frequency (GHz)

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.

0 5 10 15 2010

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WinCal SOLR



LeCroy SOLT


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.

0 5 10 15 2015

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WinCal SOLR



LeCroy SOLT


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LeCroy SOLT


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Figure 91 – CCN 100 mil Thru – SD1D1 Magnitude

Figure 92 – CCN 100 mil Thru – SC1C1 Magnitude

ISS Straight Thru Standard



Differential Impedance – (100) Ohms

Common-mode Impedance – (25) Ohms




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Figure 93 – Straight Thru Standard – SD2D1 Magnitude

Figure 94 – Straight Thru Standard – SD2D1 Phase

Figure 95 – Straight Thru Standard – SC2C1 Magnitude

Figure 96 – Straight Thru Standard – SC2C1 Phase

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Figure 97 – Straight Thru Standard – SD1D1 Magnitude

Figure 98 – Straight Thru Standard – SC1C1 Magnitude

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LeCroy SOLT


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59

Measurement Conclusions Most of the measurements show good correlation for most calibration methods except for SOLR, which

seemed to deviate from the others significantly. Also, the differential measurements showed better

correlation than the common-mode measurements.

In all measurement results, when we subsequently say “good correlation” we mean excluding SOLR and

excluding the time-domain gating method which tends to deviate from the calibration methods, but in

some cases providing more believable results (certainly in cases where passivity is violated slightly by

other methods). Again, the suspicion is that the time-domain gating removes probe tip effects.

All measurements of the LeCroy demo board showed good correlation up to 15 GHz with a +/- 1 dB

magnitude and +/- 5 degree phase difference between 15 and 20 GHz.

The measurements of the CCN 3 inch and 4.9 inch trace showing similarly good correlation.

The 100 mil thru measurement showed good correlation for the differential mode, but the common-

mode seems low at -5 dB. There was some difficulty getting a proper connection on this trace, so

perhaps there was an error in the connection that led to the low results.

The straight thru standard showed very good correlation, with about half the variation of the other

measurements.

Rev 1, September, 2011 60

Conclusions The measurements indicate that the SPARQ and Cascade Microtech probes and software work well

together to take quality S-parameter measurements. The raw measurements show good results to

30 GHz, with only a small impact of the probe on the measurement. The SPARQ’s “live” TDR/TDT mode

facilitated the measurement process, allowing users the ability to understand quickly whether the

connections to the DUT were firm.

The probes utilized are specified for 18 GHz operation, although they come with 2.92 mm connectors for

40 GHz operation). The GSSG arrangement and wide pitch required for these specific PCB measurements

were the main bandwidth limitation. Narrower pitches and other probe tip configurations like GSGSG

offered by Cascade offer better performance.

When using Cascade Microtech probes and WinCal XE software with a SPARQ, users have access to a

variety of precision calibration methods, along with well-integrated software packages; WinCal XE

outputs error terms that the SPARQ application can import directly.

The calibrations showed consistent differential measurement results. There are variations in loss

occurring under certain circumstances; the common-mode measurements showed more variation in

loss and the SOLR calibration showed more variation than the other methods.

The impedance traces showed varying degrees of tip interaction with the DUT traces, indicating that

much of the variation in results (certainly in return loss measurements) potentially is due to the

different DUT and calibration standard probing environments. In this area, the time-domain gating

seemed to perform better since the de-embedded element considers the tip interaction.

As expected, the LeCroy SOLT calibration measurements were seen to be identical to the WinCal XE

SOLT calibration measurements. Thus, WinCal XE is not required to perform this type of calibration with

the SPARQ, Cascade Microtech probes and calibration substrates (although the user must generate the

models of the standards). Users certainly have the benefit of a variety of choices for calibration method.

Finally, the WinCal XE hybrid LRRM-SOLR calibration provided the most consistent comparisons, with the

time-domain gating also providing consistent results.

Documents

LeCroy SPARQ and Cascade Microtech Probes Using WinCal XE Calibrationscdn.teledynelecroy.com/files/appnotes/lecroy_sparq... · 2011-10-06 · LeCroy SPARQ and Cascade Microtech Probes