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
LeCroy Demo Board Trace Measurements, continued
Figure 38 - LeCroy Demo Board – WinCal XE Hybrid SOLT-SOLR Calibration
Figure 39 - LeCroy Demo Board – WinCal XE Hybrid LRRM-SOLR Calibration
31
LeCroy Demo Board Trace Measurements, continued
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
CCN Three Inch Trace Measurements, continued
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
CCN Three Inch Trace Measurements, continued
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
CCN 4.9 Inch Trace, continued
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
CCN 4.9 Inch Trace, continued
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
CCN 100 Mil Thru, continued
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
CCN 100 Mil Thru, continued
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
Cascade ISS Straight Thru Standard, continued
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
Cascade ISS Straight Thru Standard, continued
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
LeCroy Time-domain Gating
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
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2040
30
20
10
0
10
20
30
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
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
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 20100
80
60
40
20
0
20
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
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
Differential Delay – 418 ps
Common-mode Delay – 475 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) – 6.5 dB
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
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
8
6
4
2
0
2
4
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 20100
80
60
40
20
0
20
40
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
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
LeCroy Time-domain Gating
frequency (GHz)
magn
itu
de (d
B)
.
0 5 10 15 20200
150
100
50
0
50
100
150
200
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
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
Differential Delay – 675 ps
Common-mode Delay –770 ps
Differential Impedance – 106 Ohms
Common-mode Impedance – 46 Ohms
Time-domain Gating Adjustment – 4.5 ps
Differential Loss @ 20 GHz – 6 dB
Common-mode Loss @ 20 GHz (in common-mode reference impedance) – 10 dB
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
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
2
4
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 20200
150
100
50
0
50
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
0 5 10 15 2015
10
5
0
5
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 20200
150
100
50
0
50
100
150
200
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
54
Figure 85 – CCN 4.9 Inch Trace – SD1D1 Magnitude
Figure 86 – CCN 4.9 Inch Trace – SC1C1 Magnitude
CCN 100 mil Thru
Differential Delay – 13 ps
Common-mode Delay –14 ps
Differential Impedance – (100?) Ohms
Common-mode Impedance – (25?) Ohms
Time-domain Gating Adjustment – 4.5 ps
Differential Loss @ 20 GHz – 1 dB
Common-mode Loss @ 20 GHz (in common-mode reference impedance) – 1 dB
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
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
0
2
4
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2010
0
10
20
30
40
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
0 5 10 15 2015
10
5
0
5
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2030
20
10
0
10
20
30
40
50
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
56
Figure 91 – CCN 100 mil Thru – SD1D1 Magnitude
Figure 92 – CCN 100 mil Thru – SC1C1 Magnitude
ISS Straight Thru Standard
Differential Delay – 6 ps
Common-mode Delay –8 ps
Differential Impedance – (100) Ohms
Common-mode Impedance – (25) Ohms
Time-domain Gating Adjustment – 4.5 ps
Differential Loss @ 20 GHz – 0 dB
Common-mode Loss @ 20 GHz (in common-mode reference impedance) – 0 dB
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
57
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
0 5 10 15 20
4
2
0
2
4
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2020
10
0
10
20
30
40
50
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
0 5 10 15 20
4
2
0
2
4
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2030
20
10
0
10
20
30
40
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
ph
ase
(d
eg)
.
58
Figure 97 – Straight Thru Standard – SD1D1 Magnitude
Figure 98 – Straight Thru Standard – SC1C1 Magnitude
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
0 5 10 15 2050
40
30
20
10
0
WinCal SOLT
WinCal SOLR
WinCal Hybrid SOLT -SOLR
WinCal Hybrid LRRM-SOLR
LeCroy SOLT
LeCroy Time-domain Gating
frequency (GHz)
mag
nit
ud
e (
dB
)
.
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.