In the voltage reference circuit shown in the figure, the op-amp is ideal and the transistors Q₁, Q₂,….., Q₃₂ are identical in all respects and have infinitely large values of common – emitter current gain $$\beta $$. The collector current (I_C) of the transistors is related to their base emitter voltage (V_BE) by the relation I_C = I_S exp (V_BE/V_T); where I_s is the saturation current. Assume that the voltage V_P shown in the figure is 0.7 V and the thermal voltage V_T=26mV

The output voltage V_out (in volts) is _____.

The amplifier circuit shown in the figure is implemented using a compensated operational amplifier (op-amp), and has an open-loop voltage gain, A₀ 10⁵ V/V and an open-loop cut-off frequency, f_C = 8 Hz. The voltage gain of the amplifier at 15 kHz, in V/V, is __________.

For the circuit shown in the figure, R₁ = R₂ = R₃ = 1 Ω, L = 1 µH and C = 1 µF. If the input V_in = cos(10⁶t) , then the overall voltage gain (V_out /V_in) of the circuit is __________.

In the opamp circuit shown, the Zener diodes Z1 and Z2 clamp the output voltage V_o to +5 V or -5 V. The switch S is intially closed and is opened at time t = 0

The time t = t_{1 (in seconds) at which Vo changes state is _____.}