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Vgd in breakdown in PSS analysis of VCO (Read 673 times)

gorkhim

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Vgd in breakdown in PSS analysis of VCO
Jan 22^nd, 2009, 11:20pm

Hello,
I am trying to design a VCO with a nanowire transistor (Operating Freq = 100G). Breakdown voltage for the transistor is 1.5V. I used 1V VDD and got 1Vp-p swing for transient analysis. When I started PSS, it gives warning for "Vgd in breakdown." I designed to have 600mVp-p swing and still get the same warning. Does anyone suggest me why I am getting such warnings in PSS not in transient?

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vivkr

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Re: Vgd in breakdown in PSS analysis of VCO
Reply #1 - Jan 22^nd, 2009, 11:38pm

Have you tried to plot the transient waveforms from the PSS analysis? I would look at those, including the initial transient results which are not saved by default (you need to enable that option in the PSS form).

I sometimes had the problem that spectre issued a warning about some oxide breaking down etc, but the voltages were never large enough for that. I did not see this in PSS but in plain transient sometimes.

Best regards,

Vivek

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pancho_hideboo

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Re: Vgd in breakdown in PSS analysis of VCO
Reply #2 - Jan 23^rd, 2009, 3:27am

gorkhim wrote on Jan 22^nd, 2009, 11:20pm:

When I started PSS, it gives warning for "Vgd in breakdown."

If such warnings are reported only during shooting newton iterations, generally you can ignore these warnings.
But if you see such warnings even in steady state, there exists a real problem.

http://www.designers-guide.org/Forum/YaBB.pl?num=1228240587/5#5

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