Test 1 - Analog Circuits (Electronics and Communication)

Question 1 Multiple Choice (Single Answer)

In the silicon BJT circuit shown below, assume that the emitter area of transistor Q1 is half that of transistor Q2.

The value of current I₀ is approximately

0.5 mA
2 mA
9.3 mA
15 mA

Question 2 Multiple Choice (Single Answer)

Generally, the gain of a transistor amplifier falls at high frequencies due to the

internal capacitances of the device
coupling capacitor at the input
skin effect
coupling capacitor at the output

Question 3 Multiple Choice (Single Answer)

Voltage series feedback (also called series-shunt feedback) results in

increase in both input and output impedances
decrease in both input and output impedances
increase in input impedance and decrease in output impedance
decrease in input impedance and increase in output impedance

Question 4 Multiple Choice (Single Answer)

The OPAMP circuit shown above represents a

high pass filter
low pass filter
band pass filter
band reject filter

Question 5 Multiple Choice (Single Answer)

The diodes and capacitors in the circuit shown are ideal. The voltage v(t) across the diode D₁ is

– 1 + Cos (^{$\omega t$})
sin (^{$\omega t$})
1 – cos (^{$\omega t$})
1 – sin (^{$\omega t$})

Question 6 Multiple Choice (Single Answer)

An n-channel depletion MOSFET has following two points on its I_D -V_GS curve:
(i) V_GS = 0 at I_D = 12 mA and
(ii) V_GS = - 6 volts at I_D = 0

Which of the following Q-points will give the highest trans-conductance gain for small signals?

V_GS = - 6 Volts
V_GS = - 3 Volts
V_GS = 0 Volts
V_GS = 3 Volts

Question 7 Multiple Choice (Single Answer)

The effect of current shunt feedback in an amplifier is to

increase the input resistance and decrease the output resistance
increase both input and output resistances
decrease both input and output resistances
decrease the input resistance and increase the output resistance

Question 8 Multiple Choice (Single Answer)

In the CMOS circuit shown, electron and hole mobilities are equal, and M₁ and M₂are equally sized. The device M₁ is in the linear region if

V_in< 1.875 V
V_in < 3.125 V
V_in> 3.125 V
0 <V_in < 5 V

Question 9 Multiple Choice (Single Answer)

The Op-amp circuit shown in the figure below is a filter. The type of filter and its cut-off frequency are respectively

high pass, 10000 rad/sec
low pass, 1000 rad/sec
high pass, 1000 rad/sec
low pass, 10000 rad/sec

Question 10 Multiple Choice (Single Answer)

What is the frequency of radio waves radiated out by an oscillating circuit consisting of condenser of capacity 0.02 microfarad and inductance 8 microhenry?

3.98 x 10⁵ Hz
4.56 x 10⁵ Hz
6.21 x 10⁴ Hz
7.12 x 10⁴ Hz

Question 11 Multiple Choice (Single Answer)

Consider the common emitter amplifier shown below with the following circuit parameters.

B = 100, g_m = 0.3861 A/V, r₀= ^_$\infty$, r_p = 259 W, R_S = 1 kW, R_B = 93 kW, R_C = 250 W, R_L = 1 kW, C₁= ^_$\infty$ and C₂ = 4.7 mF.

The lower cut-off frequency due to C₂ is

33.9 Hz
27.1 Hz
13.6 Hz
16.9 Hz

Question 12 Multiple Choice (Single Answer)

In a transconductance amplifier, it is desirable to have

a large input resistance and a large output resistance
a large input resistance and a small output resistance
a small input resistance and a large output resistance
a small input resistance and a small output resistance

Question 13 Multiple Choice (Single Answer)

Consider the common emitter amplifier shown below with the following circuit parameters.

B = 100, g_m = 0.3861 A/V, r₀= ^_$\infty$, r_p = 259 W, R_S = 1k W, R_B = 93kW, R_C = 250 W, R_L = 1k W, C₁= ^_$\infty$and C₂ = 4.7mF.

The resistance seen by the source Vs is

258^$\Omega$
1252^$\Omega$
93 K^$\Omega$
$\infty$

Question 14 Multiple Choice (Single Answer)

The input resistance R_i of the amplifier shown in the figure is

$\dfrac{30}{4}K\Omega$
10 k^$\Omega$
40 k^$\Omega$
infinite

Question 15 Multiple Choice (Single Answer)

The current i_b through the base of a silicon npn transistor is 1 + 0.1 cos(10000 ^_$\pi$t) mA. At 300 K,
the r$\pi$ in the small signal model of the transistor is

250^$\Omega$
27.5^$\Omega$
25^$\Omega$
22.2^$\Omega$

Question 16 Multiple Choice (Single Answer)

Choose the correct match for input resistance of various amplifier configurations shown below.|||
|---|---|
| Configuration| Input resistance|
| CB: Common Base| O: Low|
| CC: Common Collector| MO: Moderate|
| CE: Common Emitter| HI: High|

CB-LO, CC-MO, CE-HI
CB-LO, CC-HI, CE-MO
CB-MO, CC-HI, CE-LO
CB-HI, CC-LO, CE-MO

Question 17 Multiple Choice (Single Answer)

The voltage gain A_v of the circuit shown below is

|A_v| ^_$\approx$200
|A_v| ^_$\approx$100
|A_v| ^_$\approx$20
|A_v| ^_$\approx$10

Question 18 Multiple Choice (Single Answer)

Directions: Consider the CMOS circuit shown below, where the gate voltage v₀ of the n-MOSFET is increased from zero, while the gate voltage of the p −MOSFET is kept constant at 3 V. Assume that, for both transistors, the magnitude of the threshold voltage is 1 V and the product of the trans-conductance parameter is 1 mAV^-2.

For small increase in V_G beyond 1 V, which of the following gives the correct description of the region of operation of each MOSFET?

Both the MOSFETs are in saturation region.
Both the MOSFETs are in triode region.
n -MOSFET is in triode and p −MOSFET is in saturation region.
n -MOSFET is in saturation and p −MOSFET is in triode region.

Question 19 Multiple Choice (Single Answer)

Directions: Consider the CMOS circuit shown, where the gate voltage v₀ of the n-MOSFET is increased from zero, while the gate voltage of the p−MOSFET is kept constant at 3 V. Assume that, for both transistors, the magnitude of the threshold voltage is 1 V and the product of the trans-conductance parameter is 1 mA V^-2.

Estimate the output voltage V₀ for V_G = 15 V.

4 - ^{$\dfrac{1}{\sqrt2}$}
4 + ^{$\dfrac{1}{\sqrt2}$}
4 - ^{$\dfrac{\sqrt3}{2}$}
4 + ^{$\dfrac{\sqrt3}{2}$}

Test 1 - Analog Circuits (Electronics and Communication)

Questions