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May 21st, 2024, 10:46pm
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How to simulate the loop gain in switch cap.? (Read 5644 times)
sch
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How to simulate the loop gain in switch cap.?
Apr 07th, 2003, 6:29pm
 
If I am running a switch capacitor sigma-delta converter, and
want to see  how about  the on resistance of the switch affect
the loop gain by simulator (Spectre RF or Spice). How should I do ?
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Jitter Man
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Am I? Or am I so
sane that u just
blew your mind?

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Re: How to simulate the loop gain in switch cap.?
Reply #1 - Apr 8th, 2003, 3:13pm
 
Which loop gain are you referring to?
1. The loop gain of a single integrator?
2. The loop gain of the filter alone (generally multiple loops)?
3. The loop gain of the converter?
In the last case, at any instant, the loop is open,  so you must be thinking of the loop gain in some average sense.

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sch
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Re: How to simulate the loop gain in switch cap.?
Reply #2 - Apr 8th, 2003, 6:59pm
 
If I am referring to the single integrator loop gain , what command in SpectreRF that I can use to find out the loop gain
vs. frequency?
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Jitter Man
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Am I? Or am I so
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Re: How to simulate the loop gain in switch cap.?
Reply #3 - Apr 8th, 2003, 9:27pm
 
Spectre has a conventional small signal analysis, stb,  that computes the loop gain. That will work fine if you believe you can turn off the clock while measuring loop gain. Otherwise you will need to use the techniques described in Section 3.4.1 of Kundert's book. Of course, with the clock being active, you will have to substitute SpectreRF's PAC analysis for the AC analysis used in the book.

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