Do you have basic knowledge of RF circuit theory although "RF" is included in your name "viva
rf" ?
Maybe you are "
unvivarf".
You should learn small signal analysis with a starter of the following post.
http://www.designers-guide.org/Forum/YaBB.pl?num=1236321645vivarf wrote on Mar 17th, 2009, 8:36pm:The original definition: Y21=Id/Vin
Here Id and Vin are both small signal value in AC Analysis.
vivarf wrote on Mar 17th, 2009, 8:36pm:The result you defined is taken out current: Y21=i("/M2/D" ?result "ac") (single-ended)
This is because I set Vin as 1.0V in AC analysis.
You might think calculation of g2 and g3 is irregular since it uses both DC analysis result and AC analysis result.
But it is matched to an actual measurements using actual instruments.
S-parameters are measured by Vector Network Analyzer(SP-Analysis) with sweeping DC bias points feeded via Bias-Tee.
Y21 is evaluated from S-parameters. g2 and g3 are calculated by derivation of g1=real(Y21) regarding DC bias points difference.
I always say to people in this Forum, "You have to learn measurements using actual instruments". Not "EDA Tool Play". vivarf wrote on Mar 17th, 2009, 8:36pm:From the original definition, I thought Y21 = deriv(i("/M2/D" ?result "ac"))
No. You are still misunderstanding
the original definition.
You can't understand gm in DC Analysis and Y21 in AC analysis.
First of all, you can't understand small signal analysis such as AC, XF, SP Analysis at all.
Learn Y,Z,S-Prameters of linear system.
Maybe you are student. So discuss such too basic issues with friends.