Stats

  • Locked Locked
  • Replies 6
  • Subscribers 126
  • Views 5899
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Complex Port Value for transient results

EngrZM

Hi

I am trying to run the transient analysis (Cadence Virtuoso ADE L) on an SnP file of a transformer layout. The s-parameter results are not consistent with the transient results. I am using complex impedance values at the input and output of the transformer. I tried different accuracy methods and algorithms available in transient analysis settings, but the results were not similar to the S-parameter results. I want to ask: is there any possibility that transient analysis is not supported with complex port values? The setup diagram is attached. please guide. Thank you

Parents Reply Children
  • in reply to Frank Wiedmann

    Thanks Frank. I thought I'd answered this yesterday but I don't see it (so maybe I didn't press the "Reply" button and got distracted).

    The help for "spectre -h port" makes it very clear that this is only supported for frequency domain analysis (see the descriptive part at the top of the help, plus the specific documentation for the "x" parameter in the Port Parameters section). As Frank mention (and I tried to write yesterday) the issue would be that a constant complex impedance would not be causal in the time domain and is non-physical.

    Andrew

  • in reply to Andrew Beckett

    Thanks Frank and Andrew for always being available to help cadence community. 

    I got consistent S-parameter and transient results for the transformer (passive structure) simulation using port with real values only. But when i am simulating a differential amplifier, i am not getting transient results same as S-parameters. I am using 100 ohm input port (50 ohm imp of each transistor in the differential pair) and terminating it with 100 ohm port (differential output), as it works well with s-parameter simulations.

    Can we use 100 ohm single port for differential amplifier (50-50 matched) input/output in transient analysis?  For transient analysis i tried it in 4 configurations shown below:




  • in reply to EngrZM

    I looks like you forgot to add a gnd symbol to your circuit.

  • in reply to Frank Wiedmann

    The results are same even with ground terminal at center.

  • in reply to EngrZM

    That surprises me. Anyway, you might want to take a look at the ideal_balun from analogLib, which is explained in detail at designers-guide.org/.../diff.pdf

    Oh, and if the output amplitude is your problem: specify the source amplitude in V instead of dBm, so that it does not depend on the port impedance. The internal source will have twice the value specified, so that you get the specified value when the load is matched to the port impedance.

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.