Showing posts with label BJT. Show all posts
Showing posts with label BJT. Show all posts

Monday, April 26, 2010

BJT vs. MOSFET gain comparison

for a mosfet in common source configuration
voltage gain A_mos = -gm*(ro||RD||RL)

and for a BJT in common emitter configuration,
A_bjt = -gm*(ro||RC||RL)

where, ro = output resistance = VA/IC or ID, VA=early voltage, IC=bias collector current and gm =transconductance parameter

considering RC=RD and load, RL to be the same, what can be said about the relative values of A_mos and A_bjt. What would be the comparitive relation between the values of gm and ro of both devices in general.?

Saturday, September 19, 2009

CMOS over BJT's

What are the advantages of using CMOS instead 0f BJTs for realizing digital circuits?

Thursday, July 30, 2009

some problems plz help!

my queries! 1.how can we get a 3/2 clock,ie a clock output with high for 1 and a half cycle of input clock and low for one clock cycle of input? 2.why do constant current source made from BJT have high gain? 3.why is offset voltage present in saturated BJT and not in MOSFET? 4.how does putting a source follower as output stage in opamp help in avoiding loss of gain when a low value load resistor is connected to amplifier? 5.in what cases do v need to double clock a signal before presenting to a synchronous state machine? 6.why do v need to put a gate resistance in mosfet circuits? 7.you have a driver that derives a long signal & connects to an input device. at the input device ther is either overshoot,undershoot or signal threshold violations,what can be done to correct this problem?