Electronics

Electronics

Transistor co-simulation

    • vinay91
      Subscriber

      Hi,


      This is a general query in the realm of transistor circuit design at high frequencies. I have a transistor circuit that I am trying to extensively simulate in HFSS at W band and higher. All the transistor terminals are contacted to M1, the first layer of the metal. This query consists of two parts :


      1. I would like to simulate test structures for the bare transistor first. I have a functional physics based model in ADS, and I would like to create a wrapper around the model to simulate the effects of the pad and the contacting structures. How would I be able to do this, and what ports would I use in HFSS - lumped or wave? Since the transistor dimensions are about 1% or so of the wavelength, I presume these would be lumped ports?


      2. Next, I would like to set the simulation up for a complete end to end analysis of my input and output matching, and transistor contacts. In this case, I would like to contact the transistor through some length of metal, and then de-embed to see the performance of the transistor itself. Would the ports in this case be wave ports since there is some length of transmission line to excite the appropriate mode in the transistor?


      3. I understand that HFSS also supposedly has a RF option that makes it easier to run harmonic balance and other advanced non-linear frequency based analysis techniques. How can this be enabled/bought?


      I would like it if someone could either answer these questions with examples/screenshots, or point me in the direction of material I can use to understand this. 

    • slouie
      Ansys Employee

      Hi vinay91,


      1. I assume the geometry lends itself better to the use of lumped ports rather than waveports (which require PEC backing). 


      2. In this case, you would use waveports since lumped ports do no allow you to deembed out the length of transmission line. 


      3. Yes, RF Option opens up non-linear circuit solvers such as harmonic balance. You may already have this license, but if not, please reach out to your ANSYS account manager for details around how to obtain this license. 

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