In the circuit shown below, $$V_1$$ and $$V_2$$ are bias voltages. Based on input and output impedances, the circuit behaves as a

A cascade of common-source amplifiers in a unity gain feedback configuration oscillates when

The $$\mathrm{{{{V_{OUT}}} \over {{V_{IN}}}}}$$ of the circuit shown below is

In the circuit shown below, D$$_1$$ and D$$_2$$ are silicon diodes with cut-in voltage of 0.7 V. $$\mathrm{V_{IN}}$$ and $$\mathrm{V_{OUT}}$$ are input and output voltages in volts. The transfer characteristic is