Question

H5P1 ZERO-OFFSET AMPLIFIER

In many amplifiers, we use dual power supplies so we can obtain a 0V offset at the output, that is, the DC operating point at the output is 0V. An example amplifier circuit that can achieve this is shown below.
In this circuit, VS+=1.0V, VS−=−1.0V, and the MOSFET parameters are K=1 mAV2 and VT=0.5V.
what formulas do i need

Answer 1

here i shall guide u through the solution ,
we have to find max Vin ;
to find Vin let us apply kvll to the input loop
Vin - Vgs+1 =0;
ie, Vin = Vgs-1 ...............................(eqn1)
now the unknown parameter is Vgs, hence to find it
lets apply KVL to external loop :
1-Ids*R-Vds+1=0 ,
further substituting the value of Ids = k/2 *(Vgs-Vt)^2 in the above equation and solving the quadratic equation we will get,
Vds = 0.593, -0.84 : as Vds needs tobe +ve hence neglecting he -ve term we have
Vds = 0.593
and we know Vds = Vgs-Vt
ie Vgs = Vds+Vt
therefore, Vgs = 0.593+0.5=1.093
and substituting the above valuw in eqn1 we have
Vin=1.093-1=0.093

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