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Simulators >> Circuit Simulators >> how to plot intrinsic frequency ?
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Message started by nus_lin on Apr 7^th, 2005, 9:02am

Title: how to plot intrinsic frequency ?
Post by nus_lin on Apr 7^th, 2005, 9:02am

Dear andew and ken,

last time i ask how to plot gm over I, and what you told me did work. however, plotting intrinsic frequency over I is much more complex. can you spend some time to drop down your solution? i am using analog artist with simulator=spectre.

btw, may i save an expression base on a transistor's op point? say gm/cgs?

Title: Re: how to plot intrinsic frequency ?
Post by Andrew Beckett on Apr 7^th, 2005, 1:12pm

I don't know exactly what you mean by intrinsic frequency (please elaborate), but answering your second question might answer it for you.

You don't need to save an expression in spectre, but if you do:

Code:

save m1:gm m1:cgs

or just:

Code:

save m1

(which will save all operating point data for a specific transistor), you can then compute gm/cgs in the calculator. If you can plot gm versus I, and cgs versus I, then in the calculator dividing the two will give gm/cgs versus I.

Whatever calculation you need to do to compute intrinsic frequency, can be done in this way.

Regards,

Andrew.

Title: Re: how to plot intrinsic frequency ?
Post by James on Apr 7^th, 2005, 6:38pm

Do you mean intrinsic frequency "gm*ro"?

Title: Re: how to plot intrinsic frequency ?
Post by nus_lin on Apr 7^th, 2005, 7:13pm

James wrote on Apr 7^th, 2005, 6:38pm:

Do you mean intrinsic frequency "gm*ro"?

this is intrinsic gain.

Title: Re: how to plot intrinsic frequency ?
Post by James on Apr 7^th, 2005, 7:22pm

Then what do you mean intrinsic frequency?

Title: Re: how to plot intrinsic frequency ?
Post by nus_lin on Apr 8^th, 2005, 12:41am

ideally, it is the frequency that the gain of input current equals to output current.