Assume that the OP-AMP in the figure, ideal
- Obtain an expression for $v_{0}$ in terms of $v_{s}, \mathrm{R}$, and the reverse saturation current $I_{s}$ of the transistor.
- If $\mathrm{R}=1 \; \Omega, \mathrm{I}_{\mathrm{s}}=1 \; \mathrm{pA}$ and the thermal voltage $\mathrm{V}_{\mathrm{T}}=25 \; \mathrm{mV}$, then what is the value of the output voltage $v_{\mathrm{o}}$ for an input voltage $v_{\mathrm{s}}=1 \mathrm{~V}$ ?
- Suppose that the trarsistor in the feedback path is replaced by a $p-n$ junction diode with a reverse saturation current of $\mathbf{I}_{s}.$ The $p$-side of the diode is connected to node $\mathrm{A}$ and the $n$-side to node $\mathrm{B}$. Then what is the expression for $v_{0}$ in terms of $v_{s}, R$ and $I_{s}$ ?