Download Aptitude Crack
img not found img not found

Basic Op-Amp Circuits - Technical MCQs

Q1:

If the value of resistor Rf in an averaging amplifier circuit is equal to the value of one input resistor divided by the number of inputs, the output will be equal to

A the average of the individual inputs

B the inverted sum of the individual inputs

C the sum of the individual inputs

D the inverted average of the individual inputs

ANS:D - the inverted average of the individual inputs

Problems state that if Rf=Rin/# of inputs then Vo is ?

For an averaging amplifier, Rin is equal for all inputs and the formula for Vo is,
Vo = (-Rf)(Sum of Inputs/Rin) but since Rf = Rin/(# of inputs) then,
Vo = -(Rin/(# of inputs))((Sum of Inputs)/Rin), Rin would cancel and you would have,
Vo = -((Sum of Inputs)/(# of inputs)), which is basically an inverted(negative) average of the individual inputs.