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Modeling >> Behavioral Models >> idt () function in spectre
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Message started by anurag on Mar 7^th, 2010, 3:31pm

Title: idt () function in spectre
Post by anurag on Mar 7^th, 2010, 3:31pm

Hi,

I am using a behavioral voltage source in spectre to generate desired waveform.

expression : bsource v= idt(v(Vin,0))

with the above expression, I am getting the convergence problem. I tried setting the initial condition from analog design design environment but couldn't resolve it.

I would be thankful if someone could point out the issue with this expression.

Title: Re: idt () function in spectre
Post by Geoffrey_Coram on Mar 8^th, 2010, 5:34am

anurag wrote on Mar 7^th, 2010, 3:31pm:

expression : bsource v= idt(v(Vin,0))

I don't use bsource much myself, but what about

expression : bsource v= idt(v(Vin), 0)

Note the change in parentheses.

Title: Re: idt () function in spectre
Post by anurag on Mar 8^th, 2010, 8:08am

Thanks for your reply Geoffrey.

idt function takes only 1 argument. In verilog-A, we can give the initial condition by giving 2 arguments in idt function but not in spectre.

I am able to resolve this problem by skipping the dc analysis. I am not sure whether skipping dc will create problem in rest of my circuit or not.

Title: Re: idt () function in spectre
Post by Andrew Beckett on Mar 8^th, 2010, 1:51pm

spectre has been enhanced to allow more than one argument for idt in a bsource expression, and this was added in MMSIM71 ISR9 (in July 2009). I just tried it with the latest ISR, and it works fine.

Regards,

Andrew.