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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> CMOS PA Design Question https://designers-guide.org/forum/YaBB.pl?num=1149168507 Message started by nikogian on Jun 1st, 2006, 6:28am |
Title: CMOS PA Design Question Post by nikogian on Jun 1st, 2006, 6:28am Hi all, I am trying to design an RF CMOS PA and I face the following problem: I am biasing the PA at 0.5V using a voltage swing of 0.6V (trying for it to be class B) with a fairly large FET (W = 3200 u, L = 0.35u). When I simulate the PA, the Fet seems to never turn off and always draws DC current from the source! however when I use a smaller FET the problem ceases to exist and the PA works fine. I also see an abnormal spike in small frequences during the AC simulation when I use the large FET. Is this normal? I suspect it's a parasitic effect that must be faced. The frequency of operation is 2.4GHz. I can post the simulation results if it helps Thanks in advance, Giannis |
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