Given r d = 20 k$\Omega$, I DSS = 10 mA, V p = -8 V. ![](https://i.imgur.com/bSE7z5H.png) Z i and Z 0 of the circuit are respectively

$2\ M\Omega \quad and \quad \dfrac{20}{11} K\Omega$

Test 3 - Analog Circuits (Electronics and Communication)

Question 1 Multiple Choice (Single Answer)

In the following transistor circuit, V_BE = 0.7 V, r₃ = 25 mV / I_E, and $\beta$ and all the capacitances are very large

The mid-band voltage gain of the amplifier is approximately

- 180
- 120
- 90
- 60

Question 2 Multiple Choice (Single Answer)

In the circuit below, the diode is ideal. The voltage V is given by

min (V_i, 1)
max (V_i, 1)
min (-V_i, 1)
max (-V_i, 1)

Question 3 Multiple Choice (Single Answer)

In the circuit shown below, for the MOS transistors, $\mu_n \ C_{ox}$ = 100$\mu A / V^2$and the threshold voltage V_T = 1V. The voltage V_x at the source of the upper transistor is

1V
2V
3V
3.67V

Question 4 Multiple Choice (Single Answer)

In the following transistor circuit, V_BE = 0.7 V, r₃ = 25 mV / I_E and $\beta$ and all the capacitances are very large.

The value of DC current I_E is

1 mA
2 mA
5 mA
10 mA

Question 5 Multiple Choice (Single Answer)

Consider the Op-Amp circuit shown in the figure.

The transfer function V₀ (s) / V_i (s) is

$ \dfrac {1-sRC}{1+sRC}$
$ \dfrac {1-sRC}{1+sRC}$
$ \dfrac {1}{1-sRC}$
$ \dfrac {1}{1+sRC}$

Question 6 Multiple Choice (Single Answer)

The input impedance (Z_i) and the output impedance (Z₀) of an ideal trans - conductance (voltage controlled current source) amplifier are

Z_i = 0, Z₀ = 0
Z_i = 0, Z₀ = $\infty$
Z_i = $\infty$, Z₀ = 0
Z_i = $\infty$, Z₀ = $\infty$

Question 7 Multiple Choice (Single Answer)

Assuming the OP-AMP to be ideal, the voltage gain of the amplifier shown below is

$ - \dfrac{R_2}{R_1}$
$ - \dfrac{R_3}{R_1}$
$ - \dfrac{R_2 || R_3}{R_1}$
$ - \dfrac{R_2 || R_3}{R_1}$

Question 8 Multiple Choice (Single Answer)

Consider the Op-Amp circuit shown in the figure.

If V_i = V₁ sin ($\omega t$) and V₀ = V₂ sin ($\omega t$+ $\phi$), the minimum and maximum values of $\phi$(in radians) are respectively

$ \dfrac{-\pi}{2} and \dfrac{\pi}{2}$
0 and $\dfrac{\pi}{2}$
-$\pi$ and 0
$ \dfrac{-\pi}{2}$ and 0

Question 9 Multiple Choice (Single Answer)

A bipolar transistor is operating in the active region with a collector current of 1 mA. Assuming that the $\beta$ of the transistor is 100 and the thermal voltage (V_T) is 25 mV, the transconductance (g_m) and the input resistance ($r_x$)the transistor in the common emitter configuration, are

g_m = 25 mA/V and $r_x$= 15.625 k$\Omega$
g_m = 40 mA/V and $r_x$= 4.0 k$\Omega$
g_m = 25 mA/V and $r_x$= 2.5 k$\Omega$
g_m = 40 mA/V and $r_x$= 2.5 k$\Omega$

Question 10 Multiple Choice (Single Answer)

If the input to the ideal comparator shown in figure is a sinusoidal signal of 8V (peak to peak) without any DC component, then the output of the comparator has a duty cycle of

$\dfrac{1}{2}$
$\dfrac{1}{3}$
$\dfrac{1}{6}$
$\dfrac{9}{12}$

Question 11 Multiple Choice (Single Answer)

Consider the following circuit using an ideal OPAMP. The I - V characteristic of the diode is described by the relation I = I_{0$e^{\left (\frac{V}{V1}-1 \right)}$}where V_T = 25 mV, I₀ = 1$\mu$A and V is the voltage across the diode (taken as positive for forward bias). For an input voltage V_i = - 1 V, the output voltage V₀ is

0 V
0.1 V
0.7 V
1.1 V

Question 12 Multiple Choice (Single Answer)

Given r_d = 20 k$\Omega$, I_DSS = 10 mA, V_p = -8 V.

Z_i and Z₀ of the circuit are respectively

2 M$\Omega$ and 2 k$\Omega$
$2\ M\Omega \quad and \quad \dfrac{20}{11} K\Omega$
Infinity and 2 k$\Omega$
$Infinity \quad and \quad \dfrac{20}{11} K\Omega$

Question 13 Multiple Choice (Single Answer)

In the op-amp circuit given in the figure, the load current i_L is

$ - \dfrac{V_s}{R_2}$
$ \dfrac{V_s}{R_2}$
$- \dfrac{V_s}{R_L}$
$ \dfrac{V_s}{R_1}$

Question 14 Multiple Choice (Single Answer)

For the BJT Q_L in the circuit shown below,
$\beta = \infty$, $V_{BE_{on}} = 0.7, V_{CE_{sat}}$0.7V. The switch is initially closed. At time t = 0, the switch is opened. The time t at which Q₁ leaves the active region is

10 ms
25 ms
50 ms
100 ms

Question 15 Multiple Choice (Single Answer)

Consider the Schmidt trigger circuit shown below:
A triangular wave which goes from - 12 V to 12 V is applied to the inverting input of OPMAP. Assume that the output of the OPAMP swings from + 15 V to - 15 V. The voltage at the non-inverting input switches between

− 12 V to + 12 V
- 7.5 V to 7.5 V
- 5 V to + 5 V
0 V and 5 V

Question 16 Multiple Choice (Single Answer)

A small signal source V_i = A cos 20 t + B sin 10⁶ t is applied to a transistor amplifier as shown below. The transistor has $\beta$= 150 and h_ie = 3 $\Omega$. Which expression best approximate V₀ (t)?

V₀ (t) = - 1500 (A cos 20 t + B sin 10⁶ t)
V₀ (t) = - 150 (A cos 20 t + B sin 10⁶ t)
V₀ (t) = - 1500 B sin 10⁶ t
V₀ (t) = - 150 B sin 10⁶ t

Question 17 Multiple Choice (Single Answer)

For a BJT the common base current gain $\alpha$ = 0.98 and the collector base junction reverse bias saturation current I_CO 0.6$\mu A$. This BJT is connected in the common emitter mode and operated in the active region with a base drive current I_B = 20XA. The collector current I_C for this mode of operation is

0.98mA
0.99mA
1.0mA
1.01mA

Question 18 Multiple Choice (Single Answer)

An ideal sawtooth voltage waveform of frequency 500 Hz and amplitude 3 V is generated by charging a capacitor of 2 $\mu$F in every cycle. The charging requires

constant voltage source of 3 V for 1 ms
constant voltage source of 3 V for 2 ms
constant current source of 3 mA for 1 ms
constant current source of 3 mA for 2 ms

Question 19 Multiple Choice (Single Answer)

Given, r_d = 20 k$\Omega$, I_DSS = 10 mA, V_p = -8 V

Transconductance in milli-Siemens (mS) and voltage gain of the amplifier are respectively

1.875 mS and 3.41
1.875 mS and - 3.41
3.3 mS and -6
3.3 mS and 6

Question 20 Multiple Choice (Single Answer)

Given r_d = 20 k$\Omega$, I_DSS = 10 mA, V_p = -8 V.

I_D and I_DS under DC conditions are respectively

5.625 mA and 8.75 V
4.500 mA and 11.00 V
7.500 mA and 5.00 V
6.250 mA and 7.50 V

Test 3 - Analog Circuits (Electronics and Communication)

Questions