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Phase Noise and Jitter

pcardoso73

Hi all,

I am designing a PLL on 130 um technology. At this point, I would like to calculate the phase noise of the VCXO (Crystal oscillator). But for that I wanted the simulation only to take into account the last simulation points (since the wave is stabelized), this way I think the result is more accurate. Should I use strobing for this ? Imagine I am doing a 500us simulation, running at 80 MHz. My version of Virtuoso is 6.1.4. How can I calculate phase noise only during the period the wave is stabilized and how to convert it to jitter ? I am integrating phase noise with integ command. Is his correct ? One las question, how can I speed the transient simulation time ?

 Best regards,

Pedro Cardoso

Parents
  •  Hi Andrew,

     Thanks very much for your answer. I will try to be clear.

    I am designing a VCXO in 130 um technology, and I would like to simulate the phase noise. So I did the analysis on the following order:

    1 - Transient Analysis

    2 -  PSS analysis

    3 -  Pnoise Analysis

     The issue is I am designing two Pierce oscillators, one in Strong Inversion and the other one in Weak Inversion and when I try to simulate their phase noise, the following happens:

    1 - The PSS analysis of the strong inversion circuit converges

    2- The PSS on weak inversion circuit doesn't (It says the signal is too small, despite being 300 mV peak-to-peak)

     

    Despite this, I believe that the simulated phase-noise is wrong. So I thought that might happen if I was calculating the phase noise for all the time, and not for the time it stabilizes only. For example, my simulation runs for 800 us. The wave amplitude starts growing until 500u and then stabilizes. So I would like to simulate only between 500us and 800us, and simulate the phase noise then.

     Best regards,

    Pedro Cardoso
Reply
  •  Hi Andrew,

     Thanks very much for your answer. I will try to be clear.

    I am designing a VCXO in 130 um technology, and I would like to simulate the phase noise. So I did the analysis on the following order:

    1 - Transient Analysis

    2 -  PSS analysis

    3 -  Pnoise Analysis

     The issue is I am designing two Pierce oscillators, one in Strong Inversion and the other one in Weak Inversion and when I try to simulate their phase noise, the following happens:

    1 - The PSS analysis of the strong inversion circuit converges

    2- The PSS on weak inversion circuit doesn't (It says the signal is too small, despite being 300 mV peak-to-peak)

     

    Despite this, I believe that the simulated phase-noise is wrong. So I thought that might happen if I was calculating the phase noise for all the time, and not for the time it stabilizes only. For example, my simulation runs for 800 us. The wave amplitude starts growing until 500u and then stabilizes. So I would like to simulate only between 500us and 800us, and simulate the phase noise then.

     Best regards,

    Pedro Cardoso
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