# Output voltage of differential amplifier

## Homework Statement

Find output voltage of differential amplifier having differential gain of 100 and common mode gain 0.1 if input voltages are v1=2+0.55sinwt and v2=0.5-0.005sinwt

## The Attempt at a Solution

well, from sedra smith book i found the formula for output book

if i have to subtract two AC signals with dc offsets i get v1-v2= 1.5+0.55sinwt am i correct?

so can right it as 2.11sinwt
again for Acm i have to take average of two signals which will be 1.25+0.272sinwt

i have to divide it by 2 hence it becomes 1.522sinwt

the final ans i am getting is 211.15sinwt am i correct?

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rude man
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## Homework Statement

Find output voltage of differential amplifier having differential gain of 100 and common mode gain 0.1 if input voltages are v1=2+0.55sinwt and v2=0.5-0.005sinwt

## The Attempt at a Solution

well, from sedra smith book i found the formula for output book

if i have to subtract two AC signals with dc offsets i get v1-v2= 1.5+0.55sinwt am i correct?
so can right it as 2.11sinwt
????

again for Acm i have to take average of two signals which will be 1.25+0.272sinwt

i have to divide it by 2 hence it becomes 1.522sinwt
????
You don't divide the average by 2 again! And what happened to the dc term?

the final ans i am getting is 211.15sinwt am i correct?[/QUOTE]

Don't think so.
Your starting formula is correct but then you seem to be floundering with the math.