Operational Amplifier · Analog Circuits · GATE ECE

An ideal OPAMP circuit with a sinusoidal input is shown in the figure. The 3 dB frequency is the frequency at which the magnitude of the voltage gain decreases by 3 dB from the maximum value. Which of the options is/are correct?

The number of times the LED glows is ______.

The load current I₀ through R_L is

The value of $${{{V_{OB}}} \over {{V_{OA}}}}$$ is _____

The opamps in the circuit shown are ideal, but have saturation voltages of ±10 V.

Assume that the initial inductor current is 0 A. The input voltage (Vi) is a triangular signal with peak voltages of ±2 V and time period of 8 μs. Which one of the following statements is true?

In the circuit below, the opamp is ideal.

If the circuit is to show sustained oscillations, the respective values of $R_1$ and the corresponding frequency of oscillation are ____.

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

A sample and hold circuit is implemented using a resistive switch and a capacitor with a time constant of 1 $$\mu$$s. The time for the sampling switch to stay closed to charge a capacitor adequately to a full scale voltage of 1 V with 12-bit accuracy is ___________ $$\mu$$s (rounded off to two decimal places).

A circuit with an ideal OPAMP is shown. The Bode plot for the magnitude (in dB) of the gain transfer function (A_v(j$$\omega$$) = V_out(j$$\omega$$)/V_in(j$$\omega$$)) of the circuit is also provided (here, $$\omega$$ is the angular frequency in rad/s). The values of R and C are __________.

The output voltage V_out (in volts) is _____.

The output voltage (in millivolts) is ________.

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

and V is the voltage across the diode (taken as positive for forward bias). For an input voltage $${V_i}\,\, = \,\, - 1V,$$ the output voltage V₀ is

A triangular wave which goes from -12V to 12V is applied to the inverting input of the OP-AMP. Assume that the output of the OP-AMP swings from +15V to -15V. The voltage at the non-inverting input switches between.

If $${V_i} = {V_1}\,\,\sin \left( {\omega \tau + \phi } \right),$$ then the minimum and maximum values of $$\phi $$ (in radians) are respectively

The transfer function $${V_o}\left( s \right)/{V_i}\left( s \right)$$ is

In the figure shown above, the OP-AMP is supplied with $$ \pm $$ 15V.

(a) Obtain an expression for V₀ in terms of V_s, R, and the reverse saturation current I_s of the transiostor.

(b) If R = 1$$\Omega $$, I_s = 1pA and the thermal voltage V_T = 25mV, then what is the value of the output voltage V₀ for an input voltage V_s = 1V?

(c) Suppose that the transistor in the feedback path is replaced by a p-n junction diode with a reverse saturation current of I_s. The p-side of the diode is connected to node A and the n-side to node B. Then what is the expression for V₀ in terms V_s, R and I_s ?

The characteristics of the diode are given by the relation I = I_s $$\left[ {{e^{{{qV} \over {KT}}}} - 1} \right],$$

Where V is the forward voltage across the diode
(a)Express V₀ as a function of V_i assuming V_i> 0.
(b)If R = 100K$$\Omega $$ , I_s = 1$$\mu $$A and $${{KT} \over q}\,\, = \,\,25mV$$

when $${R_a}\, = \,{R_b}\, = \,{R_c}\,{R_d}\,$$ ohms.
when $${R_a}\, = \,{R_b}\, = {R_c}\, = 100$$ ohms and $${R_{d\,}}\, = \,120$$ ohms.