Two perfectly matched silicon transistors are connected as shown in the figure. Assuming the $$\beta $$ of the transistors to be very high and forward voltage drop to be $$0.7V,$$ the value of current $${\rm I}$$ is (assume diode $$(D)$$ is ideal)

The equivalent circuits of a diode, during forward and reverse biased conditions are shown in figure.
(a)
(b)

If such diodes are used in the clipper circuit of figure given above, the output voltage (V₀) of the circuit will be

In the voltage doubler circuit shown in figure, the switch $$' S '$$ is closed at $$t=0$$. Assuming diodes $${D_1}$$ & $${D_2}$$ to be ideal, load resistance to be infinite and initial capacitor voltages to be zero, the steady state voltage across capacitors $${C_1}$$ & $${C_2}$$ will be

Figure shows a feedback system where $$K>0$$

The range of $$k$$ for which system is stable will by given by