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JC

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How to measure NMF(Noise Modulating Function)
May 22^nd, 2007, 12:37pm

Recently I am trying to simulate the ISF(Impulse Sensitity Function) for my VCO using Spectre. I have to measure the NMF for transistor's drain thermal noise. I have two methods as shown in the following figure.

The second method is approximately derived from the frist one, because I don't konw clearly how to measure the drain noise current correctly.

My questions: 1. How to measure drain noise current using Spectre?
2. Is there other methods to measure NMF?

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sheldon

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Re: How to measure NMF(Noise Modulating Function)
Reply #1 - May 24^th, 2007, 5:22am

JC,

�It may not help you directly, but there is another figures of Oscillator
merit the perturbation projection vector, PPV. For more information, see
Frank Wiedmann's comment in the following e-mail,
http://www.designers-guide.org/Forum/YaBB.pl?num=1179739160/1#1
or the following reference,
<<reference to chapter 2 of Hegazi, Rael, and Abidi (http://www.designers-guide.org/Books/dg-osc/index.html) was deleted by forum administrator>>

� The good news is that SpectreRF will directly output the PPV for a VCO. To save
the PPV, in the PSS window:
select "Oscillator" then "options", in the options window select "save osc ppv".
You can use the Results Browser to access the PPV.

� Best Regards,

Sheldon

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« Last Edit: May 24^th, 2007, 8:07am by Forum Administrator »

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JC

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Re: How to measure NMF(Noise Modulating Function)
Reply #2 - May 25^th, 2007, 6:41am

Sheldon,
�Thanks for your help.
�Unfortunately the Cadence version IC5104 doesn't contail this option in PSS simulation. So I cann't see anything about PPV. Is the PPV contained in this version (IC5104)?

� Another quesion is: If I have to use the second method described above, How to get threshold voltage? Can I just treat threshold voltage as a constant value? Dose this impact the accuracy a lot?

JC

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