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Simulators >> Circuit Simulators >> long transient analysis
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Message started by steven on Nov 20^th, 2006, 3:51pm

Title: long transient analysis
Post by steven on Nov 20^th, 2006, 3:51pm

Hi,

I have a Spectre transient analysis which takes long time to finish. In fact, the circuit is simple but there are many DC voltage sources acting as control signals. The transient analysis is carried on each set of these control signals. For example, there are 10 DC sources named as from vt1 to vt10. Each vt can have values either 0v or 5v. The transient analysis needs to be done with all combinations of vt1, vt2, ..., vt10 (A lot of them!!). A node crossing point needs to be measured during the transient analysis too.

I am wondering if there is any automation way to do that?

Thanks

Title: Re: long transient analysis
Post by vivkr on Nov 20^th, 2006, 11:28pm

steven wrote on Nov 20^th, 2006, 3:51pm:

Hi Steven,

Could you describe your block a little better? Is it a DAC or something? Are these vt1, vt2, ..., vt10 square waves or pulsed waveforms? There are various ways of speeding up things in Spectre. Depending on your circuit, one or more of these may work well.

E.g., when simulating a DAC, even a simple R-ladder DC, many people will try to measure the DC characteristic by updating the DAC code in a transient analysis. This is wasteful. One can use a DC analysis and add some AHDL/Verilog block to convert the analog input to a DAC code in such a case.

One of the easiest things to do is of course to increase the rise/fall times of any pulsed waveforms. Many users set these to a very small value and this causes problems. If you could specify what kind of circuit it is, then it would be best. Otherwise, it is hard to say what would work best for you.

Regards
Vivek