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how to simulate gm of the amplifier

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jingxuelu

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Hi,
I'm designing a gm-c integrator, and I'm going to plot the gm of the amplifier with respect to input signal amplitude. So How to plot such curve in spectres ? Thank you
 

Usman Hai

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I dont know about gm-c filter, however if you are trying to find the gm of the input transistor then you could do the following thing.
Make a text file and write this line of code

simulator lang=spectre
save M0:gm

where MO is the input transistor. In the Analog Artist window, include this file as the stimulus file, so that while simulating spectre can pick it up. Now if you sweep some parameters (dc or trans) and look in "Result Browser" then you can easily plot "gm". This process is true for all transistor parameters inside.

I hope it will help you. If so, then please click the "helped" button. Thanks
 

    jingxuelu

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ashish_chauhan

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Well what Usman has said is true but valid only for single stage amps...

If u are using Hspice or its derivatives then you can go for transfer function calculations.. this will give you the dc gain and the output resistance of ur amp.

now Gain= Gm*Ro...

hope this gives the idea for ur " How to ..."
 

LvW

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I'm designing a gm-c integrator, and I'm going to plot the gm of the amplifier with respect to input signal amplitude.

Please realize that the transconductance gm of an active device is dependent on its bias conditions but not on the signal amplitude !
 

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