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PSS, PNOISE and Transient Noise

pcardoso73

Hi all,

 I have several questions which i will describe by topics. All the circuit design is made in Candence using Spectre.

 1 - As transient noise introduces noise in the transient simulation, I export the data to Matlab to perform the Jitter (RMS and Peak-to-Peak) calculations. How can I do this in Cadence ?

2 - How can be compared the results obtained from MatLab (from Cadence exported data), and those obtained by cadence ?

3 - What kind of noise is introduced by transient noise ? Can this noise be upconverted into phase noise ?

4 - Calculating phase-noise using PSS+PNOISE, if done with transient noise on, will affect the phase noise analysis result ? Should I disable the transient noise, when performing PSS and PNOISE ?

 5 - I am designing a VCXO for a PLL. The requirements are: frequency - 80 MHz, tunning range - +- 8 kHz, cload 15 pF. To simulate this circuit with transient noise I have used the following parameters:

Noise Fmax 1e9
Noise Fmin 10k
Noise Seed 1
Noise scale 1
Noise Tmin 4u

Is this correct ?

 

Thanks To all.

 

Best regards,

Pedro 

Parents

  •  Hello,

    Thanks for your answers.

    Relating to point 4, so if I choose either transient noise analysis or transient analysis without checking the transient noise analysis, the result of the Phase-Noise/Jitter calculations will be the same on the two cases, right ?

    Relating to your question in point 5, I was using transient noise to calculate the value of jitter in Matlab (both Jcc and Peak-to-Peak) and than to draw an histogram.

    I have as well calculated the Phase-noise under Cadence (as described in the manual), and I have used another approach integrating the waveform (being the units linear). The value of RMS Jitter that I have obtained is completely different from the calculated one and the one given by the Cadence simulation

    Regarding the circuit, is a basic Crystal Pierce oscillator (three-point oscillator), being the crystal modeled by an RLC series.

     Thanks a lot,

    Pedro

Reply

  •  Hello,

    Thanks for your answers.

    Relating to point 4, so if I choose either transient noise analysis or transient analysis without checking the transient noise analysis, the result of the Phase-Noise/Jitter calculations will be the same on the two cases, right ?

    Relating to your question in point 5, I was using transient noise to calculate the value of jitter in Matlab (both Jcc and Peak-to-Peak) and than to draw an histogram.

    I have as well calculated the Phase-noise under Cadence (as described in the manual), and I have used another approach integrating the waveform (being the units linear). The value of RMS Jitter that I have obtained is completely different from the calculated one and the one given by the Cadence simulation

    Regarding the circuit, is a basic Crystal Pierce oscillator (three-point oscillator), being the crystal modeled by an RLC series.

     Thanks a lot,

    Pedro

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