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Simulators >> Circuit Simulators >> Hysteresis check using spectre
https://designers-guide.org/forum/YaBB.pl?num=1149316063

Message started by always@smart on Jun 2^nd, 2006, 11:27pm

Title: Hysteresis check using spectre
Post by always@smart on Jun 2^nd, 2006, 11:27pm

Dear all,

I wanna check the hysteresis with dc in spectre.

So far I'm checking the result by setting >DC analysis> Design Variable>

1st run : Start =1.0 , Stop= 1.4, Step Size= 0.01, using calculator plot output
2nd run: Start= 1.4, Stop= 1.0, Step Size=-0.01, using calculator plot output

I think this method is just toublesome (if i wanna check for all PVT), I tried to use parametric sweep with step size, but it is able to step from 1.0 ~1.4 , it can't sweep reversely.

Can someone please suggest me a simpler method to chech hysterisis using spectre?

Regards,
Smart

Title: Re: Hysteresis check using spectre
Post by mikki33 on Jun 3^rd, 2006, 4:30am

try to use transient with PWL at the input changing very slowly. For ex. start from 1V and go to 1.4 in 1 us and after go back to 1 in another us. The result will be very close to DC (the slower the input changes the better you accuracy).

If your curcuit (comparator???) is clocked define the accuracy by changing input signal during 1 clock cycle. (for ex. if you want 1 mV accuracy, make the input changing 1 mV during 1 clock cycle).

Title: Re: Hysteresis check using spectre
Post by always@smart on Jun 3^rd, 2006, 5:04am

Hi Mikki33,

Yeah, this is a good way. Thank you for your suggestion

So there is no better way for DC analysis?

Regards,
Smart

Title: Re: Hysteresis check using spectre
Post by Jess Chen on Jun 3^rd, 2006, 8:25am

I not sure but I think the parameteric DC sweep uses the solution at the last parameter value in the sweep as the initial guess for the solution at the next sweep value. If that is indeed true, you could see hytsteresis from a DC sweep... if you could do the reverse direction. If you really want to use the DC sweep, you could try introducing an intermediate variable, say x, and set x equal to a periodic function of the actual sweep parameter. For example, suppose you want to sweep a voltage from -1 to 1 volts and then back to -1 volts. Define x(y)=-cos(y) in your ADE window and then sweep y from 0 to 2pi.