#1 21672908 05 Dec 2014 10:08 John Alo John Alo Anonymous Post #1 21672908 05 Dec 2014 10:08 Hey, I'd like to understand why for circuit a, in the gain calculation, why they wrote vout/Rd, instead of Vout-Vdd/Rd?
#2 21672909 05 Dec 2014 22:10 Neil Mula Neil Mula Anonymous Post #2 21672909 05 Dec 2014 22:10 Hi John,It is in AC model, Vdd is usually used only during DC analysis. I think it is assumed to be zero since the effect is relatively small compared to the current flowing ro Ii.You can check it in Electronic Devices and Circuit Theory by Boylestad and Nashelskyunder FET Small-Signal Analysis.Hope it helps.Best,Neil
#3 21672910 06 Dec 2014 01:21 Richard Gabric Richard Gabric Anonymous Post #3 21672910 06 Dec 2014 01:21 The power supply, in theory , should have zero impedance from DC out to an infinite frequency, therefore Vdd is effectively at ground. The load resistor is often shown going to ground for the purposes of AC analysis.Cheers,Richard
