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Simulators >> RF Simulators >> LC VCO Simulation using SPECTRE
https://designers-guide.org/forum/YaBB.pl?num=1074043292

Message started by junkwar2003 on Jan 13^th, 2004, 5:21pm

Title: LC VCO Simulation using SPECTRE
Post by junkwar2003 on Jan 13^th, 2004, 5:21pm

I am trying to run a standard CMOS LC VCO [cross-coupled Tank LC VCO] simulation in SPECTRE.
I am using TSMC25u provided Inductors and Varacters and such, basically all real elements.
I cannot get the circuit to oscillate. I read that in spectre you need to provide a start up to get
the oscillation going. I have tried injecting ipulse, vpulse, psin source in the output node of the
oscillator to get to start switching but still no luck. I was wondering if anyone know a magic trick
to run LC VCO simulation in SPECTRE. Any hints would be helpful. Thanks

-Parag

Title: Re: LC VCO Simulation using SPECTRE
Post by Mighty Mouse on Jan 13^th, 2004, 10:46pm

The need to kick-start oscillators is not unique to Spectre, it is necessary with all simulators. There are two basic approaches that can be used, you can either apply initial conditions to one or both of the resonator components, or you can inject a transient signal into the resonator. With LC oscillators, I would recommend injecting a sinusoidal current into the resonator with a damping factor. Ken has a section in his book on this.

- MM -

Title: Re: LC VCO Simulation using SPECTRE
Post by junkwar2003 on Jan 16^th, 2004, 5:54pm

I got the ossc. to start using ipulse but thanks for your response.

Parag