ELEX

In an ideal differential amplifier shown in the figure, a large value of (R_E):

Decreases the common mode gain only.

Increase both the differential and common-mode gains.

Increases the common mode gain only.

Decreases the differential mode gain only.

The Fourier transform of a conjugate symmetric function is always:

Real

Conjugate anti-symmetric

Conjugate symmetric

Imaginary

For a BJT, the common base current gain α = 0.98 and the collector base junction reverse bias saturation current I_CO = 0.6 μA. This BJT is connected in the common emitter mode and operated in the active region with a base drive current I_B = 20 μA. What is the collector current IC for this mode of operation?

1.0 mA

0.98 mA

1.01 mA

0.99 mA

The circuit in the figure is a:

Band-pass filter

Low-pass filter

Band-reject filter

High-pass filter

In a transconductance amplifier, it is desirable to have:

A large input resistance and a large output resistance

A small input resistance and a small output resistance

A small input resistance and a large output resistance

A large input resistance and a small output resistance

The impurity commonly used for realizing the base region of a silicon n-p-n transistor is:

Gallium

Boron

Phosphorus

Indium

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

Decrease in both input and output impedances

Increase in input impedance and decrease in output impedance

Increase in both input and output impedances

Decrease in input impedance and increase in output impedance

The input impedance (Zi) and the output impedance (Z₀) of an ideal transconductance (voltage controlled current source) amplifier are:

Zi = ∞, Z₀ = ∞

Zi = 0, Z₀ = 0

Zi = 0, Z₀ = ∞

Zi = ∞, Z₀ = 0

The cascade amplifier is a multistage configuration of:

CE–CB

CC–CB

CB–CC

CE–CC

The voltage e₀ is indicated in the figure has been measured by an ideal voltmeter. Which of the following can be calculated?

Bias current of the inverting input only

Input offset current only

Both the bias currents and the input offset current

Bias current of the inverting and non-inverting inputs only

Introducing a resistor in the emitter of a common amplifier stabilizes the dc operating point against variations in:

Only the temperature

Only the β of the transistor

Both temperature and β

None of the choices

Crossover distortion behavior is characteristic of:

Class A output voltage

Class B output stage

Class AB output stage

Common-base output stage

Consider the following two statements:

Statement 1: Astable multivibrator can be used for generating square wave.

Statement 2: Bistable multivibrator can be used for storing binary information.

Only statement 1 is correct

Only statement 2 is correct

Both the statements 1 and 2 are correct

Both the statements 1 and 2 are incorrect

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

Coupling capacitor at the input

Internal capacitance of the device

Skin effect

Coupling capacitor at the output

If for a silicon npn transistor, the base-to-emitter voltage (V_BE) is 0.7 V and the collector-to-base voltage (V_CB) is 0.2 V, then the transistor is operating in the:

Cutoff mode

Normal active mode

Saturation mode

Inverse active mode

In a negative feedback amplifier using voltage-series (i.e. voltage-sampling, series mixing) feedback:

Ri increases and R₀ decreases

Ri increases and R₀ increases

Ri decreases and R₀ decreases

Ri decreases and R₀ increases

An ideal op-amp is an ideal:

Current controlled current source

Voltage controlled current source

Voltage controlled voltage source

Current controlled voltage source

The most commonly used amplifier is sample and hold circuits is:

A unity gain inverting amplifier

A unity gain non-inverting amplifier

An inverting amplifier with a gain of 10

An inverting amplifier with a gain of 100

Negative feedback in an amplifier:

Increases frequency and phase distortions

Reduces gain

Reduces bandwidth

Increases noise

Choose the correct match for input resistance of various amplifier configurations shown below:

Configuration Input resistance

CB: Common Base LO: Low

CC: Common Collector MO: Moderate

CE: Common Emitter HI: High

CB – LO, CC – HI, CE – MO

CB – HI, CC – LO, CE – MO

CB – LO, CC – MO, CE – HI

CB – MO, CC – HI, CE – LO

A master-slave flip flop has the characteristic that:

Both the master and the slave states are affected at the same time

Change in the output immediately reflected in the output

Change in the output occurs when the state of the master is affected

Change in the output occurs when the state of the slave is affected

Given figure is the voltage transfer characteristic of:

An NOMS inverter with enhancement mode transistor as load

An NMOS inverter with depletion mode transistor as load

A BJT inverter

A CMOS inverter

The effect of current shunt feedback in an amplifier is to:

Increase the input resistance and decrease the output resistance

Increases both input and output resistance

Decrease the input resistance and increase the output resistance

Decrease both input and output resistance

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

N-MOSFETs is in triode and p-MOSFET is in saturation region

N- MOSFET is in saturation and p-MOSFET is in triode region

Both the MOSFETs are in saturation region

Both the MOSFETs are in triode region

The first dominant pole encountered in the frequency response of a compensated op-amp is approximately at:

100 MHz

1 MHz

10 kHz

5 Hz

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