cylin
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Thanks for your reply.
My test examples as attached. One is chargebased varactor model and the other one is the capacitancebased varactor model. I expected to see the same result as the one shown in the document. Are there anything wrong? Could someone give an example?
By the way, the document mentioned that "A telltale symptom of this problem is that an anomalous DC current appears to flow through the varactor. This problem does not occur if (2) is used.". However, it shows the discrepency in the CV plot. This is also one of my questions.
test_varactor_c.scs // varactor test circuit simulator lang=spectre include "varactor_c.scs" section=moscap Vt (n 0) vsource mag=1 Xv (n 0) varactor capacitanceInF ac freq=1/(2*M_PI) start=2 stop=2 dev=Vt param=dc save Xv:1
varactor_c.scs // simulator lang=spectre insensitive=yes library test_varactor section moscap // subckt varactor ( p n ) parameters c0=1p c1=0.5p v0=0 v1=1 cg ( p n ) bsource c=c0+c1*tanh((v(p,n)v0)/v1) ends varactor endsection moscap endlibrary test_varactor_q.scs // varactor test circuit simulator lang=spectre include "varactor_q.scs" section=moscap Vt (n 0) vsource mag=1 Xv (n 0) varactor capacitanceInF ac freq=1/(2*M_PI) start=2 stop=2 dev=Vt param=dc save Xv:1
varactor_q.scs // simulator lang=spectre insensitive=yes library test_varactor section moscap // subckt varactor ( p n ) parameters c0=1p c1=0.5p v0=0 v1=1 cg ( p n ) bsource q=c0*v(p,n)+c1*v1*ln(cosh((v(p,n)v0)/v1)) ends varactor endsection moscap endlibrary test_varactor
