In the circuit shown below, the input voltage 𝑉𝑖𝑛 is positive. The current (𝐼) – voltage (𝑉) characteristics of the diode can be assumed to be 𝐼

Q. In the circuit shown below, the input voltage 𝑉_𝑖𝑛 is positive. The current (𝐼) – voltage (𝑉) characteristics of the diode can be assumed to be 𝐼 = 𝐼₀𝑒^𝑉/𝑉𝑇 under the forward bias condition, where 𝑉_𝑇 is the thermal voltage and 𝐼₀ is the reverse saturation current. Assuming an ideal op-amp, the output voltage 𝑉_𝑜𝑢𝑡 of the circuit is proportional to

Ans: 𝑒^𝑉𝑖𝑛/𝑉𝑇

Sol:

By applying KCL at node O,