Stats

  • Locked Locked
  • Replies 11
  • Subscribers 128
  • Views 14462
  • 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

Question on PSS+PNoise simulation for a Track and Hold circuit

YutaoLiu

Hi everyone,

I am studying how to run PSS+PNoise sim to get total output noise of a Track and Hold circuit. 

I am using Virtuoso version ICADVM20.1-64b.500.15 for simulation.

Below is my test bench, in which the switch is driven by a 8GHz 25% duty cycle clock. The closed switch resistance is 0.1Ohm, while the open resistance is 1T Ohm. And the RC time-constant is 15GHz, which is higher than the Nyquist frequency (4GHz).

In document "Simulating Switched-Capacitor Filters with SpectreRF" , it is written that the total noise of T/H circuit is kT/C, which is 41.4nV^2 in this case. 

I expect that the noise higher than 4GHz would be folded back into 0~4GHz, so I set the output frequency is from 1~4GHz. And to get a more result, maximum sideband was set as 50 (Because 4GHz *50= 200GHz >> 15GHz).

However, the total noise integrating from 1Hz to 4GHz is only 27nV^2. Moreover, the total noise increases as the duty cycle decreases. 

Did I misunderstand anything about the total noise of T/H or do anything wrong in the simulation setup?

Thanks and regards,

Yutao

       

  • Andrew Beckett
    in reply to YutaoLiu

    Yutao,

    If you don't want to set the sampling point based on a signal crossing a given threshold, then edge crossing (or edge delay) don't really make sense. Instead used the sampled phase. You will need to have at least one point per period (I think), but you can then just also list the specific times (there can be more than one) you want to sample at in the Add Specific Point field.

    Andrew.

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.