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Seeking for Help in PSS Analysis

Xuijing
Hi i am a beginner in using Cadence. I am designing a LNA and i meet problem when come to PSS analysis. My pss analysis could not run and terminated. I am clueless and have no idea. Could anyone please help? Here i attached my schematic and the simulation log pictures.
PSS analysis.pdf
Parents

  •  Dear Xujing,

    > I tried to run transient analysis but the simulation keep running nonstop and never come to the end.

    Perhaps I was not clear in my responses [2] and [3] and I am sorry for that! From your simulation log, it appears you did not follow my suggestions as the value of maxstep is much larger than my suggested value of less than 1.6ps and the value of relotl = 1e-3 (=> errpreset is "moderate", not "conservative").

    If you look at your transient simulation log in your most recent post, the value of maxstep is set to 200us with a value of tstop of 10 ms. If you look at the timesteps being chosen in the output log, they are on the order of 10 ps - which is 20 periods of your 5 GHz input clocks!!

    If your transient analysis does not produce accurate results, the pss analysis will also not produce valid results. 

    As I noted in response [2], the difference in the period of your two 5 GHz and 5.04 GHz inputs is on the order of 1.6 ps. You need to set maxstep (the maximum integration step) in the transient panel under "options" to, for example, 1 ps or less and choose an errpreset on the Transient Analysis GUI of "moderate", or perhaps better "conservative". You also do not need to run the simulation for 10 ms - that is far too long to observe the time where a steady-state solution is evident.

    I hope these suggestions make more sense now Xujing.

     

    Shawn

     

Reply

  •  Dear Xujing,

    > I tried to run transient analysis but the simulation keep running nonstop and never come to the end.

    Perhaps I was not clear in my responses [2] and [3] and I am sorry for that! From your simulation log, it appears you did not follow my suggestions as the value of maxstep is much larger than my suggested value of less than 1.6ps and the value of relotl = 1e-3 (=> errpreset is "moderate", not "conservative").

    If you look at your transient simulation log in your most recent post, the value of maxstep is set to 200us with a value of tstop of 10 ms. If you look at the timesteps being chosen in the output log, they are on the order of 10 ps - which is 20 periods of your 5 GHz input clocks!!

    If your transient analysis does not produce accurate results, the pss analysis will also not produce valid results. 

    As I noted in response [2], the difference in the period of your two 5 GHz and 5.04 GHz inputs is on the order of 1.6 ps. You need to set maxstep (the maximum integration step) in the transient panel under "options" to, for example, 1 ps or less and choose an errpreset on the Transient Analysis GUI of "moderate", or perhaps better "conservative". You also do not need to run the simulation for 10 ms - that is far too long to observe the time where a steady-state solution is evident.

    I hope these suggestions make more sense now Xujing.

     

    Shawn

     

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