Question

Consider the circuit shown below. Assume that the op-amp is ideal.

fa2014_fn_diode_opamp2.png

Figure 3-1

The diode has the following I-V characteristics: iD=Is*(e^(vD/vth)-1)

where iD is the current through the diode,( Is ) is the reverse bias saturation current Vd is the voltage across the diode, and

Vth is the thermal voltage.

Derive the expression for the output voltage, Vout

, in terms of one or more of the variables Vin,R1 ,R2 , Is, and Vth .

.Vout=
so far I got =Vth ln(Id/Is +1)
Id cannot be right.