In the $\text{Op-Amp}$ circuit shown, assume that the diode current follows the equation $I=I_{S} \exp \left(V / V_{T}\right)$. For $V_{i}=2 \mathrm{~V}, V_{o}=V_{o 1},$ and for $V_{i}=4 \mathrm{~V}, V_{o}=V_{o 2}$. The relationship between $V_{o 1}$ and $V_{o 2}$ is
- $V_{o 2}=\sqrt{2}\; V_{o 1}$
- $V_{o 2}=e^{2} V_{o 1}$
- $V_{o 2}=V_{o 1} \ln 2$
- $V_{o 1}-V_{o 2}=V_{T} \ln 2$