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analogue_guy Community Member Offline Posts: 38	automated simulation of hysteresis Mar 02^nd, 2009, 12:38pm hi how do you simulate hysteresis behaviour automatically? cheers
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Andrew Beckett

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Re: automated simulation of hysteresis
Reply #1 - Mar 2^nd, 2009, 10:40pm

The conventional way is to do a DC sweep in one direction, and then a second in the opposite direction. Spectre can do this simply by adding hysteresis=yes to the dc analysis (there's a checkbox on the dc form in ADE for this too). You can also just do two dc analyses, specifying the sweeps in different directions (from a netlist).

Regards,

Andrew.

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analogue_guy

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Re: automated simulation of hysteresis
Reply #2 - Mar 3^rd, 2009, 4:35am

Andrew Beckett wrote on Mar 2^nd, 2009, 10:40pm:

The conventional way is to do a DC sweep in one direction, and then a second in the opposite direction. Spectre can do this simply by adding hysteresis=yes to the dc analysis (there's a checkbox on the dc form in ADE for this too). You can also just do two dc analyses, specifying the sweeps in different directions (from a netlist).

Regards,

Andrew.

Thanks for the answer, formerly I used always transient simulation with a voltage ramp and I wanted a setup to run plenty of monte carlo runs and just keep the hysteresis window value after every runs.

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ywguo

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Re: automated simulation of hysteresis
Reply #3 - Mar 3^rd, 2009, 10:04pm

Andrew,

I simulated hysteresis as analogue_guy did. A slowly rising/falling slope was applied to the input of DUT.

The DC hysteresis sweep is new to me. In my mind, the simulator solves the operating point of DUT in each step of a DC sweep independently. For eg., let the simulator sweep from 1V to 2V by 0.1V step. It will solve the operating point of 1.0V, 1.1V ... 1.9V, 2V respectively and independently. As well known, the hysteresis is not memoryless. The output is strongly decided by the previous state. How does spectre simulator solve this problem by DC hysteresis sweep?

Yawei

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boe

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Re: automated simulation of hysteresis
Reply #4 - Mar 4^th, 2009, 1:18am

Yawei, Quote:

... It will solve the operating point of 1.0V, 1.1V ... 1.9V, 2V respectively and independently. As well known, the hysteresis is not memoryless. The output is strongly decided by the previous state. How does spectre simulator solve this problem by DC hysteresis sweep?

Using solution of previous step as initial guess for next step reduces computation time and provides previous state.
BOE

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Andrew Beckett Senior Fellow Offline Life, don't talk to me about Life... Posts: 1742 Bracknell, UK	Re: automated simulation of hysteresis Reply #5 - Mar 4^th, 2009, 1:30am That's right - the starting point for each point in the sweep is the previous point, and so you will generally see the hysteresis. Of course, if the hysteresis is based upon some capacitative charge storage, then DC won't do - but in many cases it's sufficient (and quick!). Regards, Andrew.
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analogue_guy

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Re: automated simulation of hysteresis
Reply #6 - Mar 4^th, 2009, 7:57am

Andrew Beckett wrote on Mar 4^th, 2009, 1:30am:

That's right - the starting point for each point in the sweep is the previous point, and so you will generally see the hysteresis. Of course, if the hysteresis is based upon some capacitative charge storage, then DC won't do - but in many cases it's sufficient (and quick!).

Regards,

Andrew.

Yes, the DC sweep works, hysteresis function can be seen. But comparing the results with the transient results I can see that the circuit is less sensitive for statistical variations (using the MC).

But could you recommend me any technique to translate these results (either the DC sweep or transient) to only a number in every run (basically the difference between the two values) and I could deal only with these number afterwards.

At the moment I save the whole waveforms in both cases (DC sweep and transient). But it required more time, also post processing, so it is not that comfortable.

Cheers

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boe Community Fellow Offline Posts: 615	Re: automated simulation of hysteresis Reply #7 - Mar 5^th, 2009, 1:25am Analogue_guy, You can use function "cross" to determine where the comparator output changes. Is that what you are looking for? BOE
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analogue_guy Community Member Offline Posts: 38	Re: automated simulation of hysteresis Reply #8 - Mar 5^th, 2009, 12:16pm boe wrote on Mar 5^th, 2009, 1:25am: Analogue_guy, You can use function "cross" to determine where the comparator output changes. Is that what you are looking for? BOE Thanks, I looked for this kind of solution. I will try to do so. Cheers
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