Consider a differential amplifier circuit shown in the figure below:
If the two tansistors are exactly matched then the voltage Vs is equal to
(Assuming T1 and T2 are operating in saturation region)
Vt=0.5V,μnCox=500μA/V2 and(WL)=100
The current of both the transistors are equal since they are perfectly matched
Thus , I2=12μnCox(WL)(VGS1−Vt)2
10×10−3=12×500×10−6×100(VGS1−0.5)2
∴VGS1=VGS2=1.132 V
Thus, Vs=Vin−VGS1=3−1.132=1.868 V