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Simulators >> Circuit Simulators >> VPULSE time periods in Cadence Spectre
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Message started by vp1953 on Jun 28^th, 2011, 6:24pm

Title: VPULSE time periods in Cadence Spectre
Post by vp1953 on Jun 28^th, 2011, 6:24pm

While running simulations on Cadence spectre, I noticed that the time periods measured for VPULSE are very different from what is specified.

Eg if time period=1000ns, trise=0.1n, tfall=0.1n is specified, the actual trise and tfall are measured on the waveform browser are very different.

I am wondering what is is the reason for this.

Thank you!

Title: Re: VPULSE time periods in Cadence Spectre
Post by Ken Kundert on Jun 29^th, 2011, 9:10am

The only time I have seen this happen is when you have very large signals elsewhere in the circuit, which causes Spectre to not honor the time step control required by the source because its signal level is 'insignificant'. To avoid this, either get rid of the large signal, which often results from a current source driving an open circuit, or set the transient option relref to alllocal.

-Ken