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Design Languages >> Verilog-AMS >> frequency-dependent parameter in verilog a
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Message started by Kem on May 10^th, 2011, 8:36am

Title: frequency-dependent parameter in verilog a
Post by Kem on May 10^th, 2011, 8:36am

I'm new here and have no experience with verilog a before. I 'm working on a FET transistor model and i have to do it with verilog a. I would like to describe a noise parameter as a function of frequency.

<i_d^2>=4*R*K*T0*B*(w*Cgs)^2 / gm

I would like to know how I can implement a frequency-dependent parameter since verilog a only works in the time domain ?

thanks a lot for your help

kem

Title: Re: frequency-dependent parameter in verilog a
Post by rfidea on May 10^th, 2011, 8:57am

There is a function, flicker_noise(pwr, exp [ , name ]), that you can use for this. There is no limitation for the variable exp so you can use the function for increasing noise with frequency, if you like.

By the way, veriloga works both in frequency and time domain.

Title: Re: frequency-dependent parameter in verilog a
Post by Kem on May 10^th, 2011, 9:03am

thanks a lot for your answer!

In my case i will do it with white_noise function. Does it means i just have to create a frequency paramerter ?

kem

Title: Re: frequency-dependent parameter in verilog a
Post by rfidea on May 10^th, 2011, 9:37am

I do not understand why you should use white_noise if you would like to have a frequency dependent noise source when there is a function for that?

If you need a flat noise response for frequencies above some corner frequency and a 1/f relationship below that corner frequency you can add a white noise source and a flicker noise source by white_noise(..) + flicker_noise(..)

Title: Re: frequency-dependent parameter in verilog a
Post by Kem on May 10^th, 2011, 12:20pm

thanks for your answer. I think i have to use both of them. I have to model the transistor untill ~30 GHz. And the really interessant frequency domain is f>2 GHz

Title: Re: frequency-dependent parameter in verilog a
Post by Kem on May 16^th, 2011, 9:19am

i still haven't solved my problem. The real question is how to model the induced gate noise current of a fet transistor. Are there someone who can help me ?

thanks
kem

Title: Re: frequency-dependent parameter in verilog a
Post by Geoffrey_Coram on May 17^th, 2011, 12:51pm

Did you look at how correlated noise is done in the MOS11 model, posted on this site?

http://www.designers-guide.org/VerilogAMS/semiconductors/mos11010/mos11010.va

Title: Re: frequency-dependent parameter in verilog a
Post by Kem on May 18^th, 2011, 5:52am

Thanks for pointing out the link. I have read it but i couldn't really understand it since there are comment missing.

kem