Forum Posts

Picotest
Mar 10, 2022
In Welcome to the Forum
I have a glance to the Bode 100 application note about battery impedance testing with your current injector: https://www.omicron-lab.com/fileadmin/assets/Bode_100/ApplicationNotes/Battery_impedance/App_Note_Battery_Impedance_V2_0.pdf and I was wondering whether you see any impairment in doing the same with Tektronix MSO5.
0
1
6
Picotest
Mar 10, 2022
In Welcome to the Forum
We’re trying to determine what pitch the end user wants for their P2104A 1-port probe (https://www.picotest.com/Products_P2104A.html).
0
1
2
Picotest
Dec 23, 2021
In Welcome to the Forum
I assume using two is not beneficial with respect to matching. Or is any pair of P2105A matched?
0
1
2
Picotest
Nov 23, 2021
In Welcome to the Forum
J2120A Usage In the vast majority of cases, the line injector is almost certainly working correctly. It is often the case that the test setup impacts the results and that a large voltage drop at its output is seen. We do get many questions about the J2120A and its operation. After reading the following if you are still having issues please let us know (instructions below). Articles & App Notes Videos Measuring Power Supply Rejection Ratio (PSSR) - on a Tektronix Scope https://www.youtube.com/watch?v=8i8Pb3wY7xo&t=13s Power Supply Rejection Ratio Measurements with a 5/6 Series MSO Oscilloscope https://uk.tek.com/video/measuring-power-supply-rejection-ratio-(pssr) Power Supply Rejection Ratio (PSRR) Measurements using an Oscilloscope (Keysight) https://www.youtube.com/results?search_query=J2120A How to measure the PSRR of a power supply using the Omicron Lab Bode 100 https://www.youtube.com/watch?v=75fEwjXspbA&t=8s A few things about the J2120A To get the right results you need to understand what you are asking the J2120A to supply, in terms of current, when it is connected to a load. If you are loading the J2120A too heavily, its voltage drop can be significant. The amount of load current (out of the J2120A) is FREQUENCY DEPENDENT because the input impedance of the load (power supply input) varies with frequency and can fall if there is an input capacitor on the input of the power supply circuit. This is usually the case in normal designs. Why is this the case? Because the impedance of the input capacitor is too low in general and especially at its resonance point and this causes the circuit (load on the J2120A) to pull too much AC current through the J2120A at some frequency (not DC). As shown on the https://www.picotest.com/products_J2120A.html page in the Detailed Specifications Tab, you will see the reason for the issue. The more current, the more drop from the input of the J2120A to the output. What you have with the J2120A and an input capacitor is a very effective low pass filter. The cable impedance of any interconnects also affects the drop. The solution is to, if possible, remove the input capacitor, or replace it with a smaller cap, so that the impedance is not too low at higher frequencies. For further support… If you are still having issues we need to understand your setup. If you could send the following to info@picotest.com it would help us to help you debug what is happening and what you are seeing. A picture of the test setup A description of the circuit loading the injectors you are trying to test PSRR including the input capacitance and/or input impedance of the loading power supply What is the operating current of the load? Can you make an impedance measurement at the input to the power supply loading the J2120A?
J2120A Line Injector Useful Information content media
0
0
199
Picotest
Sep 22, 2021
In Welcome to the Forum
Can you recommend good cables to connect the J2101A to a DUT? About the PDN Cable SMA connectors. I read here that brass SMAs should be torqued to 3-5 in-lbs: https://www.microwaves101.com/encyclopedias/connector-torque SMA (stainless steel) 7-10 in-lbs (~1Nm) SMA (brass) 3-5 in-lbs (~0.4Nm) PDN cables have brass SMA connectors, but you recommend that we torque to ~1Nm – is that correct?
0
1
3
Picotest
Sep 21, 2021
In Welcome to the Forum
Customer: Hi Steve, I have my Friday’s questions for the weekend to relax with… · 1-port method - I do see that the Bode100 monitor both the voltage ahead of the reference source resistor and after the source resistor: o Why monitoring the voltage ahead of the internal resistor? o Is it because this voltage is the some of the Voltage source and the reflected one? o We do have Zref*(1+S11)/(1-S11)… As we are measuring voltage, what is S11 in this case? · 2-port shunt through - here the Bode100 monitors the voltage ahead of the DUT, without monitoring the voltage ahead of the reference source resistor: o Is the voltage seen at channel1 the sum of both incident and reflected voltage? Hope you can clarify my doubts. Steve: This effectively measures the current in the 50 and Ohm resistor and the voltage at the port. Z) V/I. The Bode 100 doesn't actually measure the S parameter S11, though computes is by solving the reflection equation you are showing. They know Zref (50 Ohms) and they know Zdut (V/I) so they can compute S11 ;) In the 2 port, they don't need to measure the current. They know the voltage before the 50Ohm resistor and also at port 2. Z=25*S21/(1-S21). S21 is determined from the voltage before the 50 Ohms and at port 2, so no need to measure port 1. Not sure that image is right, since we don't use CH1 for the 2 port measurement. Customer: Thanks Steve. I do realize that the picture I have put is not the setup for the 2-port shunt through but it is for the gain/phase measurement… My bad… Another question… With the Bode100, we do look at the voltage ahead of the Zref and the voltage across the DUT. With the scope, we cannot see the voltage ahead of the Zref, so we use the port replicator to measure the voltage after the Zref, but using the active splitter you have, we do not lose the 6dB, so all the formulas are still valid!!! The passive splitter software option takes into account this loss!!! Am I correct? Steve: Correct. And a 3 resistor Splitter has no isolation, which is bad, so should generally us a power divider. J2161A does this without loss and with much better isolation. It also is semi-differential, so it eliminates the noise from the several measurement grounds. For example AFG ground in the rear of the scope, channels at the front of the scope and ground at the DUT. Customer: Thank you, Steve!!! I am preparing a training for my European colleagues: Your lessons are fantastic!!! Steve: Thanks for the compliment, glad you like the class. Obviously, we prefer you promote J2161A ;) J2102B is common mode, so turn it 90deg. If you can ECT as it is drawn a winding will be across the DC DUT voltage. It wouldn't like that ;) Customer: Ouch… Thanks!!!
1-port and 2-port measurements content media
0
0
7
Picotest
May 14, 2021
In Welcome to the Forum
P2102A USER: I tried your Bode 100 calibration for the P2102A 2-port probe with the J2113A isolator and that did not seem to work. Should it? Steve Sandler: Sorry that didn’t work for you, but to be fair, I didn’t claim it would 😉. The J2113A is semi-floating which can cause offset errors without the grounds connected. It might work if you shorted 3 pins and left the CH2 signal pin open, but I haven’t tried it. There is another solution, but it costs a pretty penny. Literally, we’d like to measure an ideal SHORT, which of course doesn’t exist, and we can’t enter calibration parameters into the Bode 100, so the next best thing is an ideal-ish short. The P2100A-CAL board SHORT is about 200uOhms, so not low enough for ultra-low impedance. A penny is much thicker copper, so just a few uOhms, and it is large enough to achieve minimum, though non-zero, inductance. Try to use a clean penny so that you get good contact. Here are the steps. First, with the P2102A probe and J2113A isolator connected in the traditional 2-port shunt-thru configuration, select the Shunt-Thru measurement from the Impedance Analysis tab and start a new measurement. Figure 1 The Bode 100 measurement selection dialog. Select Shunt-Thru to perform the 2-port shunt-thru measurement. Using the calibration board (P2100A-CAL) that comes with the P2102A probe, start a 2-port shunt-through measurement by setting the Source level to +13dBm, the Receiver 1 attenuator to 10dB, Receiver 2 attenuator to 20dB, and the Receiver bandwidth (RBW) to 30Hz, as shown below. You could set the Receiver bandwidth higher for the open and load calibrations, but it is easy to forget to reset it, so this really works best for me. Figure 2 The Bode 100 dialog for configuring the AC sweep settings. Perform the OPEN and LOAD calibrations using the calibration PCB or any other handy OPEN and LOAD calibrators. These are not critical for ultra-low impedance measurement. Figure 3 The Bode 100 calibration dialog. Reduce the Receiver 2 attenuator to 0dB. Figure 4 Revised AC sweep dialog. Place the probe on the penny and perform the SHORT calibration using the penny as the short. Figure 5 Using a penny for the ideal-ish short. After completing all three calibrations, you can start making measurements using the probe. Figure 6 Calibration dialog after completing the three calibrations. First, as a check, I measured the post calibration results while still on the isolation pads. The impedance floor should be about 20uOhms and a few pH. Figure 7 Short measurement after calibration. Next, I measured the P2100A-CAL SHORT pad, and you can see the low frequency ground loop effect is still present, though greatly reduced by the J2113A. The SHORT pad resistance is 200uOhms and the SHORT pad inductance is about 200pH for the 1206 probe head. Note that the low frequency ground loop effect is mostly gone, but it can be misleading. There is still an error, though reduced by the J2113A. Small changes in pin resistance will still show up here in the low frequency range. Figure 8 Short measurement after calibration. I also measured some parts whose impedance I have measured previously (a “known”). I typically use 1mOhm, 500uOhm, and 250uOhm resistors, whichever is closest to the DUT value I intend to measure. Figure 9 1mOhm, 500uOhm, and 250uOhm sample measurements. I also measured a mounted 1uF, 0805 chip capacitor. The capacitance measures 930nF and the ESL measures 236pH. This is very slightly lower than the manufacturer’s datasheet reports, but certainly within 100pH. Figure 10 AVX 08053C105JAT2A 1uF 25V X7R 1uF, 0805 chip capacitor measurement. This method is not perfect, but it does offer a simple and reasonably accurate calibration method that supports measuring sub-milliohms and sub-nH using the P2102A probe with the Bode 100 VNA. For other analyzers, the full 2-port calibration is still recommended.
Another Measuring uOhms and pH with the P2102A and the Bode 100 content media
0
0
56
Picotest
May 14, 2021
In Welcome to the Forum
P2102A USER: Hey Steve, I was super-excited to get my P2102A 2-port probe, but I am trying to figure out how to calibrate it for ultra-low impedance measurements. I seem to be getting bad results, can you help? Steve Sandler: This is a great question, and I am happy to help solve this for you. A traditional Vector Network Analyzer (VNA) would require KNOWN Short-Open-Load (S-O-L) calibration for each port and a KNOWN THRU calibration. Since there is significant coupling in a probe, ISOLATION calibration is also required. The OMICRON Lab Bode 100 VNA does not support any of these calibrations, but we do have a few tricks to make this possible. First, with the P2102A probe and J2102B common mode transformer connected in the traditional 2-port shunt-thru configuration, select the Shunt-Thru measurement from the Impedance Analysis tab and start a new measurement. Figure 1 The Bode 100 measurement selection dialog. Select Shunt-Thru to perform the 2-port shunt-thru measurement. Using the calibration board (P2100A-CAL) that comes with the probe, start a 2-port shunt-through measurement by setting the Source level to +13dBm, the Receiver 1 attenuator to 10dB, Receiver 2 attenuator to 20dB, and the Receiver bandwidth (RBW) to 30Hz, as shown below. You could set the Receiver bandwidth higher for the open and load calibrations, but it is easy to forget to reset it, so this really works best for me. Note: the calibration procedure is independent of the probe head size chosen. Figure 2 The Bode 100 dialog for configuring the AC sweep settings. Perform the OPEN and LOAD calibrations using the calibration PCB or any other handy OPEN and LOAD calibrators. These are not critical for low impedance measurement. Figure 3 The Bode 100 calibration dialog. Reduce the Receiver 2 attenuator to 0dB. Figure 4 Revised AC sweep dialog. Place the probe on the ISOLATION pads (NOT the SHORT pad). Perform the SHORT calibration using the isolation pads. Figure 5 P2100A-CAL calibration board that comes with the P2102A probe. After completing all three calibrations, you can start making measurements using the probe. Figure 6 Calibration dialog after completing the three calibrations. First, as a check, I measure the post calibration results while still on the isolation pads. The impedance floor should be about 20uOhms and a few pH. Figure 7 Isolation measurement after calibration. Next, I measured the P2100A-CAL SHORT pad, and you can see the low frequency ground loop effect is still present, though greatly reduced by the J2102B. The SHORT pad resistance is 200uOhms and the SHORT pad inductance is about 200pH for this 1206 head. Figure 8 Short measurement after calibration. I also measure some parts whose impedance I have measured previously (a “known”). Preferably 1mOhm, 500uOhm, and 250uOhm resistors, whichever measured close to the nominal value. Figure 9 1mOhm, 500uOhm, and 250uOhm sample measurements. I also measured a mounted 1uF, 0805 chip capacitor. The capacitance measures 950nF and the ESL measures 211pH. This is slightly lower than the manufacturer’s datasheet reports, but certainly within 80-100pH. Figure 10 sample 1uF, 0805 chip capacitor (AVX 08053C105JAT2A 1uF 25V X7R) measurement. This method is not perfect, but it does offer a simple and reasonably accurate calibration method that supports measuring sub-milliohms and sub-nH using the P2102A probe with the Bode 100 VNA. For other analyzers, the full 2-port calibration is still recommended.
Measuring uOhms and pH with the P2102A and the Bode 100 content media
0
0
264
Picotest
May 10, 2021
In Welcome to the Forum
Yes! Click here to order a replacement cable. Product# 005-011-000001 6-Wire Cable for J2170A/J2170B $29 plus shipping
Can I order a replacement 6-Wire Cable for the J2170A/J2170B High PSRR Power Adapter that comes with Picotest injectors? content media
0
0
14
Picotest
May 04, 2021
In Welcome to the Forum
I am trying to test an input filter with the Bode 100. Since each of the BNC’s (-) are tied together it does not seem possible to test this configuration as the (-) will short out my low side filter? Do you know or have a configuration I can use for this test approach?
Input filter test content media
0
1
15
Picotest
Mar 30, 2021
In Welcome to the Forum
Extending the course access is possible only after the course expires. In the course page you will see the "Extend Video Access" button (see screenshot below for reference). By clicking on this button, the course will be extended by 1 month. Here are the extension times based on class type: Online - can be extended by 1 month for free Online & Download - can be extended 2 times for free (each extension is 1 month) Quick Download - can be extended 3 times for free (each extension is 1 month) Additional extensions may be purchased. Contact support@picotest.com for more information.
How do I extend my course access? content media
0
0
21
Picotest
Mar 24, 2021
In Welcome to the Forum
I have seen that the TDR measurement setup has the following math: FFT of the derivative of CH3 – FFT of the derivative of CH4 Although, I cannot find the math explanation for this in links and so the bibliography. Can you please share some insights or articles?
Lesson 4 question on TDR measurement setup  content media
0
1
15
Picotest
Mar 24, 2021
In Welcome to the Forum
Shall the Vpp measurements for Steve’s spreadsheet calculation of the ENOB, and the dynamic range be taken with oscilloscope probes connected and tip shorted to gnd or just unconnected scope?
0
1
11
Picotest
Mar 24, 2021
In Welcome to the Forum
Register the main account on the Picotest portal (https://picotest-portal.fedevel.education/register.html). Only the main account (yours) can share the course with other people and only the main account can download the video files. Everyone who would like access to the course will need to register on our portal: https://picotest-portal.fedevel.education/register.html After all of the accounts are registered, use the main account to create a team and assign the course to other people. Here are a few steps on how to do that: 1. Go to https://picotest-portal.fedevel.education/ 2. On the left side of the page, click on "Sharing & Teams" 3. Add people to your team using their username 4. Click on the "Share course with team" button 5. Assign the course to people by checking boxes next to their names.
0
0
28
Picotest
Mar 24, 2021
In Welcome to the Forum
You may reset your password here: https://picotest-portal.fedevel.education/forgotPassword.html
0
0
6
Picotest
Mar 11, 2021
In Welcome to the Forum
The Answer: There are many variables, but for sure below 1mOhm…. The magnitude depends on the VNA used, the cables, the ground isolator and the calibration as well as the probe attenuation. Using PDN Cables, the Bode 100, J2113A ground isolator and a 1X P2102A probe, the impedance floor below is about 30uOhms and 60pH. This is using 2-port SOL calibration, 13dBm source level and 30Hz receiver bandwidth. Theoretically a 100uOhm impedance and 180pH could be measured with reasonable accuracy. I wouldn’t specify the probe for 100uOhms, but in this example, I measured 250uOhms. The DUT is a 250uOhm Stackpole CSS2725 resistor. First, it’s essential to know the correct answer. I used the 2-port probe to measure the resistor at DC. I did this by forcing 1 amp through one port and measuring the voltage, using an accurate DMM, at the other port. The correct resistance is 275uOhm. The Bode 100 measures 276uOhms and so the probe accurately measured the 275uOhm resistor. The inductance is a bit trickier, since we don’t actually know the inductance of the short. The incremental inductance for the resistor is likely the difference between the measurement and the short. To measure this inductance accurately requires using a calibrated calibrator, or alternatively a 3D simulation of the short with the contact pins matching the probe contact point during calibration.
The Question: What is the lowest impedance I can measure with the P2102A 2-port probe? content media
0
0
107
Picotest
Feb 23, 2021
In Welcome to the Forum
We started using the J2120A injector and had question. DC input is specified 50V max. We like to know the minimum as I hope this is not issue. Ideally we like to go down to 1.2Vdc but I’m most certain this is not possible.
0
1
20
Picotest
Feb 15, 2021
In Welcome to the Forum
Please point me to videos that show the steps and benefits of PDN characterization
0
1
27
 

Picotest

Admin
More actions