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justin
Joined: 02 Jun 2004
Posts: 20
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 13 Jan 2005 10:02 How to simulate inductor in hspice99.4 |
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I have added a 10n inductor in series with vdd to simulate the actual situation(is it right?). But I now found the circuit(it is a low speed DAC, the DAC has no latch, i.e. no clock) work weirdly. when I give the digital from all 0 to all 1, it is not monotonic. but without inductor, it work well. I doubt the hspice99.4 is not so good in simulating inductor. So I put the inductor in the circuit but contact nothing, i.e. I put the inductor alone , and I found the result is not monotonic too. I think the hspice is not good at simulating inductor? Has anyone met this issue?
Thanks.
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wee_liang
Joined: 04 Jan 2005
Posts: 26
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| 13 Jan 2005 17:51 Re: How to simulate inductor in hspice99.4 |
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It's hard to believe hspice not doing a good job in simulating fundamental elements (R L C).
What kind of DAC topology did you use?
While traversing through the binary values, did you allow the output to settle down before evaluating the values? Could it be that due to high current spikes, the v=L*di/dt causes "ringing" on the vdd line, resulting in transient errors?
Is is a simple ideal inductor or some on-chip inductor models?
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layes2
Joined: 03 Dec 2004
Posts: 346
Helped: 5
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| 14 Jan 2005 10:14 Re: How to simulate inductor in hspice99.4 |
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perhaps if the speed of you circuit is high enough the ind is important
SL ok
?
hspice is good enough i think
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justin
Joined: 02 Jun 2004
Posts: 20
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| 17 Jan 2005 9:09 Re: How to simulate inductor in hspice99.4 |
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The DAC is hybrid converters, high MSBs using thermometer, while LSBs using binary code. I have given it enough time to settling down. And I have observed the vdd variation, it will settle in several nano second, and the digital code is about several kilo herz. it is a ideal inductor. In our process, it doesn't afford inductor model.
I have said I have made an experment. Other than the DAC circuit(without inductor), I have put an inductor in the circuit, but it has nothing with DAC.
But the result is uncorrect. So I doubt the reliability of the hspice tool on indcutor.
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