2 Replies Latest reply on Oct 15, 2014 7:09 AM by oscar.martinelli

    How to stimulate a PDN with a CPM model?


      An IC vendor provide the CPM (chip power model) model and i am trying to carry on further investigation on a PDN's pcb board.

      The CPM looks like a Spice model with IPWL (current source) ports that should be attached to the PCB s-paramenter model.

      The problem that i am facing now is making the IPWL Spice model working with hyperlynx.


      My question is: is it possible to implements IPWL in hyperlinx? where the stimulus is should be connect?

      Kind Regards,


        • 1. Re: How to stimulate a PDN with a CPM model?



          Setting up a PWL source is fairly easy in HyperLynx. I've attached the example files. It is a simple buffer pointing to the SPICE file which points to the PWL file terminated into a 1 Ohm resistor. You can replace the resistor with your S-Par file representing the PDN. I used to do this all the time to estimate ripple voltage.


          Create the .cir file and the PWL file using a simple text editor like notepad, then place a buffer on the schematic and point to the .cir file. The buffer should be set as an output. You can change the location of the IPWLfile to anywhere you like.


          Give it a shot and see if it works.


          The .protect and .unprotect statements are necesary to encrypt the SPICE files to run in HyperLynx.


          We have kind of an older version of HyperLynx (8.1) here so you may need to change the version number in the .ffs file at the top to open it.


          Kind regards,



          • 2. Re: How to stimulate a PDN with a CPM model?

            Dear Kirk,

            thank you for your answer.


            In your analisys do you include the VRM in your s-par (the one provied via the configuration tool)? Because the S-par start from 1Mhz, i had a few issue at DC.

            For a not clear reason, at DC, the Z of my S-par PDN seems to be very low and i have measured very hight current coming out form the VRM..

            In this I-transient analisys probably this is not an issue, but i am wondering if this can false my simulation.