Semiconductor Devices and Operational Amplifiers - Analog and Digital Electronics - Biomedical Engineering Previous Year Questions

1

2020 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2020

For the given input voltage, \( V_{in} = 10 \sin(2\pi t) \) to the functional circuit shown below, the output signal will be

A

B

C

D

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2

2020 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2020

The forward biased current of a silicon (Si) diode is being calculated from the exponential model of the V-I characteristics. If the diode current \(I_D = 1\) mA at a voltage drop \(V_D = 0.7\) V, the nearest value of \(I_D\) when \(V_D = 0.8\) V is Assume thermal voltage \(V_T = 25.3\) mV for Si diode

A

0.133 mA

B

2 mA

C

52 mA

D

90 mA

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3

2021 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2021

In the circuit diagram shown below, all OPAMPs are ideal with infinite gain and bandwidth. \(V_{OUT}/V_{IN}\) for this circuit is ______.

A

5.00

B

5.33

C

4.80

D

6.00

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4

2021 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2021

In the circuit diagram shown below, NMOS is in saturation region, \(\mu_n C_{ox} = 200 \mu A/V^2\), width W = 40 μm, length L = 1 μm, the threshold voltage is 0.4 V, and the ratio of body-effect transconductance (\(g_{mb}\)) to transconductance (\(g_m\)) is 0.1. A small input voltage \(v_{in}\) is applied at the bulk-terminal to produce a small change in the output voltage \(v_{out}\). The dc gain for \(v_{out}/v_{in}\) is ______. (Neglect channel-length modulation for NMOS and all intrinsic capacitors)

A

-0.4

B

-4.0

C

-4.4

D

-3.6

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5

2021 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2021

In the circuit shown below, the output voltage Vout is ______ V.

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6

2022 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2022

A filter is designed using opamps, resistors, and capacitors as shown below. Opamps are ideal with infinite gain and infinite bandwidth. If \(V_o(s)/V_i(s)\) is an all-pass transfer function, the value of resistor \(R2\) is ______ \(k\Omega\).

A

1

B

10

C

5

D

2

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7

2022 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2022

In the circuit diagram shown below, the MOSFET is biased in saturation region. The MOSFET has a threshold voltage \(V_{th} = 0.5 V\), width \(W = 100 \mu m\), length \(L = 0.1 \mu m\), and \(\mu_n C_{ox} = 100 \mu A/V^2\). Assuming \(v_i = 1 mV\) as a small-signal input to MOSFET, the magnitude of the output voltage \(V_o\) is ________ mV (accurate to two decimal places). Ignore channel-length modulation for the MOSFET.

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8

2022 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2022

An ideal opamp with an infinite gain and infinite bandwidth is connected in feedback as shown below. The output voltage \(V_o\) for the given input voltages in the circuit is ________ V (accurate to one decimal place).

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9

2023 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2023

In the following circuit with an ideal operational amplifier, the capacitance of the parallel plate capacitor \(C\) is given by the expression \(C = \left(\frac{\epsilon A}{x}\right)\), where \(\epsilon\) is the dielectric constant of the medium between the capacitor plates, and \(A\) is the cross-sectional area. In the above relation, \(x\) is the separation between the two parallel plates, given by \(x = x_0 + kt\), where \(t\) is time; \(x_0\) and \(k\) are positive non-zero constants. If the input voltage \(v_I\) is constant, then the output voltage \(v_0\) is given by __________.

A

\(\frac{R v_I C k}{x}\)

B

\(\frac{R v_I C}{kx}\)

C

\(\frac{v_I k}{RCx}\)

D

0

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10

2023 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2023

Assuming the operational amplifier in the circuit shown below to be ideal, which of the following properties hold(s) TRUE for the circuit?

A

It acts as a voltage follower.

B

It is bistable.

C

It is astable.

D

The output voltage is at saturation.

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11

2024 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2024

Which of the following waveforms represents the output \(V_o\) of the circuit given below? The Zener diode used has a Zener breakdown voltage of 1 V and can be assumed ideal while in forward bias.

A

B

C

D

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12

2024 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2024

In the figure below, the diode is ideal. The current reading shown in the ammeter is ______ A. Give your answer rounded off to the nearest integer.

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13

2025 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2025

In the circuit shown below, assuming an ideal op-amp, for an input voltage \(V_{in} = 1\,\text{V}\), the output voltage \(V_{out} = \_\_\_\_\_\_\_\_\_\_ \) (in volts).

A

1.0

B

2.0

C

0.5

D

0.1

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14

2025 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2025

What is the output voltage Vout for the circuit shown below? __________ (in volts, rounded off to the nearest integer).

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15

2025 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2025

The frequency of the oscillator circuit shown in the figure below is __________ kHz. (rounded off to two decimal places)
Given: R = 1 kΩ; R1 = 2 kΩ; R2 = 6 kΩ; C = 0.1 μF

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16

2026 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2026

A standard n-type MOSFET, biased in the saturation region, has the following parasitic capacitances:
1. C_GS: gate to source capacitance
2. C_GD: gate to drain capacitance
3. C_DS: drain to source capacitance
Which one of the following options is correct?

A

C_GS > C_GD > C_DS

B

C_GD > C_DS > C_GS

C

C_DS > C_GD > C_GS

D

C_GD > C_GS > C_DS

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17

2026 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2026

The \(I-V\) characteristics of a diode with a knee voltage \(V_{knee} = 0.8\) volts is shown in Figure 1. This diode is used in the circuit shown in Figure 2, in which an input signal of \(V_{in} = 100\sin(1000t)\) volts is applied. What is the voltage \(V_{out}\) (in volts) across the capacitor at steady state?
Assume that the capacitor is initially discharged and the reverse breakdown voltage of the diode is much greater than 100 volts.

A

99.2

B

99.2\cos(1000t)

C

99.2\sin(1000t)

D

-99.2

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18

2026 · Biomedical Engineering · Analog and Digital Electronics · Semiconductor Devices and Operational Amplifiers

Biomedical Engineering (BM) 2026

If the operational amplifier in the circuit below is ideal, the input impedance looking into terminal \(V_{in}\) is __________

A

\(\infty\)

B

\(-\frac{R \times R_1}{R_F}\)

C

\(\frac{R \times R_F}{R_1}\)

D

\(R\)

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