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Design >> Analog Design >> Cgd in miller effect
https://designers-guide.org/forum/YaBB.pl?num=1184136974

Message started by RobertZ on Jul 10^th, 2007, 11:56pm

Title: Cgd in miller effect
Post by RobertZ on Jul 10^th, 2007, 11:56pm

Hi, all,

In spectre's simulation result, there are Cgd and Cdg in the operation print out, and they are different (sometimes, by a lot).
Which one should be used for miller effect? |Av|*Cgd or |Av|*Cdg shows up at the gate?

Thanks,
Robert

Title: Re: Cgd in miller effect
Post by boe on Jul 11^th, 2007, 1:32am

Hi RobertZ,
I think Yawei's post helps here:

ywguo wrote on Jul 7^th, 2007, 12:20am:

Hi,
Assume you are using BSIM 3v3 model, please take a look at the definition using spectre -h bsim3v3.
Here, cdg is ΔQd/ΔVg, cgd is ΔQg/ΔVd, cgs is ΔQg/ΔVs. So it is not curious to see minus capacitance.
Yawei

So you need cgd...

Hope this helps
BOE