PSPICE-FOR-TI: How to activate lossy Transmission line

Hi Mita,

We are looking into these questions and will get back to you by tomorrow.

Thanks,
JC

JC-san,

Tank you for your feedback.

I am looking forward to get  your answers.

Mita

Hi Mita-san,

The answers to your questions will come in multiple parts.  To your first question, I am sending you a small test case using the TLOSSY transmission line model in Pspice.  It is attached.  Please let us know if you can open it in Pspice and make it run.

Best regards,

Lawrence

LA_SANDBOX_PSPICE-2020-10-15T17-52.zip

Lawrence-san,

Thank you for the design file.

I have confirmed that I can run transient simulation and get waveform.

I will toying it and run AC transfer simulation later day.

I still looking forward to get the answers to the lest of questions.

Mita

Lawrence-san,

I run simulation, checked the waveform precisely and notice that signal did not come out from the lossy trace at all

Please refer the attached file.   Green curve = Input.  Red curve=Output = 0V

Mita

Lawrence-san,

I  could resolved the Lossy trace mode issue.

I found a book which describes the PSPICE Lossy trace model.

Following the description of the book, I could get signal on output of the lossy trace model.

I put the following parameters through the PSPICE GUI.

   C =200 p

   G = 0

   L = 480 n

   LEN = 50 mm

   R = 4.5

I still looking forward to get the answers to the lest of questions.

Mita

Hi Mita-san,

Thank you for your feedback.  I am very glad that you were able to compute the transmission line parameters.  I have some documents to send to you for your Q3 on s-parameter calculations. 

1. Notes on my setup.  I used the test case from the Cadence notes (attached: doc3) to run in PSpice for TI.  This is the passive case (Butterworth). 

2. There is an bug in PSpice for TI for the test case (Butterworth).  This file shows the output.  This may be specific to the test case.

3. This is a Cadence document on getting s-parameters from PSpice.

Please let me know your thoughts on these.  Also, please let me know if you have any problems with your circuit in Pspice for TI.  I will follow up to see if the library problem described in #2 is a corner case.  We will try to resolve.  Again, you may not have a problem. 

Best regards,

Lawrence

doc1_pspice_sparameters_additional_notes.docx

doc2_pspice_output_for_passive_butterworth_sparameter.docx

doc3_pspice_for_ti_Cadence_sparameters.pdf

Hi Mita-san,

This is an update.  You had asked about PRBS7 support in PSpice.

I do not find any built-in support in PSpice for PRBS generators.  However, Cadence has good support for these devices in the Spectre simulator.  Also, Spectre has Verilog-A where one can write code to perform this function.  Thus, it is something Cadence has enabled in multiple ways but not in PSpice.

Also, I have been looking in the literature for circuit implementations that would be simple to use in PSpice.  That is still underway.

And I will ask Cadence if there is another way to do this for PSpice.  I will get back to you by Nov 10 to let you know what I find out from Cadence.

Please let me know if you have any questions.

Best regards,

Lawrence

Lawrence-san,

Thank you for your advice and I apologize delay of my response.

I am looking forward your update on Nov. 10^th.

I tried to implement the PRBS generator using Filip-Flops and XOR gate in PSPICE

Library, however, I could not run the simulation without errors.

I appreciate it if you can give me advice on how to run logic simulation.

Mita

Hello, Mita-san:

Here is an update for your questions on PRBS generator and eye diagrams in Pspice.

Cadence has confirmed that Pspice does not currently have a built-in pseudo-random binary sequence generator.  However, for now, here is a link I found on the internet that may be a possible way to proceed.  (Cadence also suggested it).

https://www.slideshare.net/azadajay/prbs-generat

For eye diagrams in Allegro Pspice, I am attaching a Cadence application note.

Please let me know if these help. I will also work on experiments using these.

Best regards,

Lawrence

eye_displays_with_pspice_cadence.pdf