Stats

  • Locked Locked
  • Replies 2
  • Subscribers 125
  • Views 14687
  • 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

Oscillator frequency discrepancy between PSS and transient simulation

Juanelin

Hi everyone,


I am designing a mm-wave Colpitts VCO and am running into big discrepancies (around 7-8 GHz) between the calculated PSS Harmonic Frequency and the calculated frequency from the transient simulations. I use harmonic balance for performing my PSS simulations with an harmonic number of 10. The version of Cadence I am using is the 6.16 and MMSIM is 14.10.

My oscillator seems to start after approx. 4 ns and I therefore set the tstab value in the PSS to 10 or 15 ns when the oscillation has already stabilized. I also set the step and maxstep from both the PSS and the transient simulation value typically to 1 ps in order to capture the oscillation behaviour. If i don't do this, Spectre can't typically resolve out the oscillation and the transient simulation shows a damped out response.

I´ve saved the initial transients (tstab) from the PSS simulations as well. Looking at them, the calculated frequency/wave seems to agree very well with my transient simulation, but if I look at the time wave from the PSS results, it does not match the obtained graph from the initial transient/transient simulations. The difference in frequency is around 7-8 GHz being the PSS calculated frequency the higher one.

Until now I´ve just tried to reduce the maxstep in the PSS options as well as use the sigglobal accuracy option to check if that improves the results agreement, but no succes by now.

I would like to ask if anyone has run into such problems and how could I solve it or at least improve the matching between my results?


Many thanks in advance.

BR

Parents

  • Hi Andrew,

    Yes of course, I will send the brief description of the problematic so you can tell me how to procceed here.

    Thanks,


    BR,

    Erick

    *UPDATE: Should I just send an e-mail with a brief description to my corresponding customer suppor contact (Germany)? Or should I fill out the Case Creation Form before? I think for accessing the online support service I have to log in with our customer main account if I am correct. Should I then contact our cadence account manager for this?


    Thanks for the reply,

    BR,

    Erick

Reply

  • Hi Andrew,

    Yes of course, I will send the brief description of the problematic so you can tell me how to procceed here.

    Thanks,


    BR,

    Erick

    *UPDATE: Should I just send an e-mail with a brief description to my corresponding customer suppor contact (Germany)? Or should I fill out the Case Creation Form before? I think for accessing the online support service I have to log in with our customer main account if I am correct. Should I then contact our cadence account manager for this?


    Thanks for the reply,

    BR,

    Erick

Children
No Data

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.