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Electronic Devices & Circuits MCQs

Practice Electronic Devices & Circuits MCQs from fundamental concepts through intermediate, advanced and application-oriented questions. Each page contains up to 100 questions with answers and explanations where available.

Question 1
Electronic Devices & CircuitsSpecial Diodes

A photodiode used as a light detector is commonly operated under?

  • AReverse bias
  • BHeavy forward bias only
  • CZero voltage in every application
  • DAvalanche breakdown necessarily
Report an error
Correct Answer: A. Reverse bias
Explanation: Photodiodes are commonly reverse biased so incident light produces a measurable photocurrent with useful response speed and sensitivity.
Reference: Standard optoelectronics: photodiode
Question 2
Electronic Devices & CircuitsSpecial Diodes

An LED emits light primarily because of?

  • ACarrier recombination in a forward-biased junction
  • BReverse-bias leakage only
  • CThermal breakdown of the junction
  • DMechanical vibration of the package
Report an error
Correct Answer: A. Carrier recombination in a forward-biased junction
Explanation: In an LED, injected electrons and holes recombine in the semiconductor and release energy as photons.
Reference: Standard optoelectronics: LED
Question 7
Electronic Devices & CircuitsSemiconductor Fundamentals

Doping pure silicon with a pentavalent impurity such as phosphorus generally produces?

  • AP-type semiconductor
  • BN-type semiconductor
  • CIntrinsic semiconductor
  • DInsulating material
Report an error
Correct Answer: B. N-type semiconductor
Explanation: Pentavalent donor atoms contribute extra electrons, making electrons the majority carriers in an n-type semiconductor.
Reference: Standard semiconductor electronics: doping
Question 8
Electronic Devices & CircuitsSemiconductor Fundamentals

In a p-type semiconductor, the majority charge carriers are?

  • AElectrons
  • BHoles
  • CNeutrons
  • DPositive ions moving through the lattice
Report an error
Correct Answer: B. Holes
Explanation: Trivalent acceptor doping creates holes as the majority mobile carriers in p-type material.
Reference: Standard semiconductor electronics: p-type material
Question 9
Electronic Devices & CircuitsPN Junction Diode

The depletion region of a PN junction mainly contains?

  • AOnly freely moving electrons
  • BOnly freely moving holes
  • CImmobile ionized donor and acceptor atoms
  • DNo electric field
Report an error
Correct Answer: C. Immobile ionized donor and acceptor atoms
Explanation: Carrier diffusion near the junction leaves uncovered fixed ionized donors and acceptors, forming the space-charge or depletion region.
Reference: Standard semiconductor electronics: PN junction
Question 10
Electronic Devices & CircuitsPN Junction Diode

Forward biasing a PN junction generally causes the depletion width to?

  • AIncrease
  • BDecrease
  • CRemain exactly unchanged
  • DBecome infinite
Report an error
Correct Answer: B. Decrease
Explanation: Forward bias opposes the built-in junction field, reducing the barrier potential and narrowing the depletion region.
Reference: Standard semiconductor electronics: diode biasing
Question 11
Electronic Devices & CircuitsPN Junction Diode

The approximate forward voltage drop of a conducting silicon diode at ordinary current levels is commonly taken as?

  • A0.1 V
  • B0.3 V
  • C0.7 V
  • D5 V
Report an error
Correct Answer: C. 0.7 V
Explanation: For basic circuit analysis, a forward-biased silicon PN diode is commonly approximated as having about a 0.7 V drop, although the actual value depends on current and temperature.
Reference: Standard electronics: silicon diode approximation
Question 12
Electronic Devices & CircuitsSpecial Diodes

A Zener diode is normally operated for voltage regulation in its?

  • AForward cut-off region
  • BReverse breakdown region
  • CZero-current region only
  • DForward saturation region
Report an error
Correct Answer: B. Reverse breakdown region
Explanation: A Zener diode is designed to operate safely in reverse breakdown, where its voltage remains approximately constant over a useful current range.
Reference: Standard electronics: Zener diode
Question 14
Electronic Devices & CircuitsOperational Amplifiers

For an ideal op-amp operating with negative feedback in its linear region, the differential input voltage V+ – V- is approximately?

  • AInfinite
  • BEqual to the supply voltage
  • CZero
  • DAlways 1 V
Report an error
Correct Answer: C. Zero
Explanation: Because an ideal op-amp has infinite open-loop gain, linear negative-feedback operation forces its two input voltages to be approximately equal, often called a virtual short.
Reference: Standard analog electronics: ideal op-amp assumptions
Question 15
Electronic Devices & CircuitsRectifiers & Filters

A capacitor filter connected across a rectifier load primarily reduces ripple by?

  • ACharging near voltage peaks and discharging through the load between peaks
  • BBlocking all DC current
  • CIncreasing the supply frequency
  • DMaking the diode permanently reverse biased
Report an error
Correct Answer: A. Charging near voltage peaks and discharging through the load between peaks
Explanation: The capacitor charges when the rectified voltage rises and supplies load current while the rectified input falls, smoothing the output voltage.
Reference: Standard electronics: capacitor filter
Question 19
Electronic Devices & CircuitsBJT Amplifiers

A common-emitter amplifier normally produces an output voltage that is approximately how far out of phase with the input voltage?

  • A0 degrees
  • B90 degrees
  • C180 degrees
  • D360 degrees only
Report an error
Correct Answer: C. 180 degrees
Explanation: A common-emitter voltage amplifier is inverting, so its output voltage is approximately 180 degrees out of phase with its input.
Reference: Standard analog electronics: common-emitter amplifier
Question 20
Electronic Devices & CircuitsBJT Amplifiers

Which BJT configuration typically has high voltage gain, high current gain, and a 180-degree phase reversal?

  • ACommon base
  • BCommon emitter
  • CCommon collector
  • DEmitter follower with unity current gain
Report an error
Correct Answer: B. Common emitter
Explanation: The common-emitter configuration provides both voltage and current gain and introduces phase inversion, making it widely used for amplification.
Reference: Standard analog electronics: transistor configurations
Question 21
Electronic Devices & CircuitsBJT Amplifiers

The common-collector BJT configuration is also called an?

  • AEmitter follower
  • BCollector follower
  • CBase follower
  • DDifferential pair
Report an error
Correct Answer: A. Emitter follower
Explanation: In a common-collector stage, the output is taken from the emitter, which approximately follows the input voltage; hence the name emitter follower.
Reference: Standard analog electronics: emitter follower
Question 22
Electronic Devices & CircuitsFET & MOSFET

A major characteristic of an ideal FET input is?

  • AVery low input impedance
  • BVery high input impedance
  • CZero output resistance in all configurations
  • DLarge gate current under normal operation
Report an error
Correct Answer: B. Very high input impedance
Explanation: A FET is voltage controlled and normally draws very little gate current, giving it high input impedance.
Reference: Standard electronics: FET characteristics
Question 23
Electronic Devices & CircuitsFET & MOSFET

For an n-channel JFET operating normally, the gate-source junction is generally?

  • AForward biased heavily
  • BReverse biased
  • CShort-circuited
  • DDriven into avalanche continuously
Report an error
Correct Answer: B. Reverse biased
Explanation: The JFET gate-channel PN junction is normally reverse biased, which keeps gate current very small and controls the channel depletion width.
Reference: Standard electronics: JFET operation
Question 24
Electronic Devices & CircuitsFET & MOSFET

An enhancement-mode n-channel MOSFET at VGS = 0 ideally has?

  • AA fully enhanced conducting channel
  • BNo induced conducting channel between drain and source
  • CMaximum drain current
  • DA forward-biased gate junction
Report an error
Correct Answer: B. No induced conducting channel between drain and source
Explanation: An enhancement-mode nMOS requires a positive gate-to-source voltage above threshold to induce a conducting channel; ideally it is off at VGS = 0.
Reference: Standard electronics: enhancement MOSFET
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Question 26
Electronic Devices & CircuitsPN Junction Diode

For a silicon PN diode carrying current in forward bias, an increase in junction temperature generally causes the forward voltage required for the same current to?

  • AIncrease
  • BDecrease
  • CRemain exactly constant
  • DBecome equal to the reverse breakdown voltage
Report an error
Correct Answer: B. Decrease
Explanation: For a silicon diode at a given forward current, the forward voltage typically decreases as junction temperature rises; a commonly used approximate coefficient is about -2 mV/°C near ordinary operating conditions.
Reference: Standard semiconductor electronics: diode temperature behavior
Question 27
Electronic Devices & CircuitsPN Junction Diode

In the ideal-diode approximation, the forward-biased diode is modeled as?

  • AAn open circuit
  • BA short circuit
  • CA current source only
  • DA capacitor only
Report an error
Correct Answer: B. A short circuit
Explanation: An ideal forward-biased diode has zero voltage drop and zero resistance, so it is represented as a short circuit.
Reference: Standard circuit analysis: ideal diode model
Question 32
Electronic Devices & CircuitsRectifiers & Filters

For a center-tapped full-wave rectifier, if Vm is the peak voltage across one half of the transformer secondary, the peak inverse voltage across each ideal diode is?

  • AVm
  • B2Vm
  • CVm/2
  • D4Vm
Report an error
Correct Answer: B. 2Vm
Explanation: In a center-tapped full-wave rectifier, the nonconducting diode can see approximately twice the peak voltage of one half-secondary, so PIV = 2Vm.
Reference: Standard electronics: rectifier PIV
Question 36
Electronic Devices & CircuitsBJT Amplifiers

Emitter degeneration using an unbypassed emitter resistor in a common-emitter amplifier generally provides?

  • APositive feedback and unstable bias
  • BNegative feedback and improved bias stability
  • CInfinite voltage gain
  • DZero input resistance
Report an error
Correct Answer: B. Negative feedback and improved bias stability
Explanation: An emitter resistor develops degenerative negative feedback, helping stabilize the operating point and improving linearity, though it reduces gain.
Reference: Standard analog electronics: emitter degeneration
Question 37
Electronic Devices & CircuitsBJT Amplifiers

A common-base BJT amplifier typically has a current gain that is?

  • AMuch greater than beta
  • BApproximately alpha and slightly less than unity
  • CExactly zero
  • DAlways negative
Report an error
Correct Answer: B. Approximately alpha and slightly less than unity
Explanation: The common-base current gain is alpha = IC/IE, normally close to but less than 1.
Reference: Standard analog electronics: common-base configuration
Question 38
Electronic Devices & CircuitsBJT Amplifiers

The voltage gain of an ideal emitter follower is approximately?

  • A-100
  • B-1
  • C0
  • D+1
Report an error
Correct Answer: D. +1
Explanation: A common-collector or emitter-follower stage has a non-inverting voltage gain slightly less than unity in practice and approximately +1 ideally.
Reference: Standard analog electronics: emitter follower
Question 40
Electronic Devices & CircuitsFET & MOSFET

An n-channel enhancement MOSFET begins forming a strong inversion channel when VGS exceeds approximately its?

  • ADrain breakdown voltage
  • BThreshold voltage
  • CGate reverse current
  • DPinch-off current
Report an error
Correct Answer: B. Threshold voltage
Explanation: The threshold voltage VTH is the gate-source voltage at which a conducting inversion channel begins to form according to the device model.
Reference: Standard electronics: MOSFET threshold
Question 41
Electronic Devices & CircuitsFET & MOSFET

In an ideal MOSFET, the DC gate current is approximately?

  • AEqual to drain current
  • BEqual to source current
  • CZero
  • DInfinite
Report an error
Correct Answer: C. Zero
Explanation: The MOS gate is insulated from the channel by an oxide layer, so ideal steady-state gate current is zero, giving very high input resistance.
Reference: Standard electronics: MOSFET gate
Question 43
Electronic Devices & CircuitsOperational Amplifiers

An ideal op-amp has input resistance and output resistance respectively equal to?

  • AZero and infinite
  • BInfinite and zero
  • CUnity and unity
  • DZero and zero
Report an error
Correct Answer: B. Infinite and zero
Explanation: The ideal op-amp draws no input current, implying infinite input resistance, and acts as an ideal voltage source at its output, implying zero output resistance.
Reference: Standard analog electronics: ideal op-amp properties
Question 45
Electronic Devices & CircuitsOperational Amplifiers

For an ideal op-amp integrator with input resistor R and feedback capacitor C, the output is proportional to?

  • AThe time integral of the input with inversion
  • BThe time derivative of the input without inversion
  • COnly the DC value of the input
  • DThe square of the input voltage
Report an error
Correct Answer: A. The time integral of the input with inversion
Explanation: An ideal inverting integrator produces Vo = -(1/RC) integral(Vin dt), within its intended operating range.
Reference: Standard analog electronics: op-amp integrator
Question 46
Electronic Devices & CircuitsOperational Amplifiers

An ideal op-amp differentiator produces an output proportional to?

  • AThe integral of input voltage
  • BThe rate of change of input voltage with inversion
  • CThe square root of input voltage
  • DA constant independent of input
Report an error
Correct Answer: B. The rate of change of input voltage with inversion
Explanation: For the ideal inverting differentiator, Vo = -RC(dVin/dt), so output is proportional to the input's time derivative with inversion.
Reference: Standard analog electronics: op-amp differentiator
Question 49
Electronic Devices & CircuitsBJT Biasing

In a DC load-line analysis of a common-emitter transistor circuit, the Q-point represents?

  • AThe maximum supply voltage only
  • BThe quiescent DC operating point
  • CThe transistor breakdown point only
  • DThe AC frequency response
Report an error
Correct Answer: B. The quiescent DC operating point
Explanation: The Q-point specifies the transistor's steady DC collector current and collector-emitter voltage with no input signal applied.
Reference: Standard analog electronics: transistor biasing
Question 50
Electronic Devices & CircuitsBJT Biasing

For symmetrical maximum undistorted voltage swing in a simple class-A common-emitter stage, the Q-point is commonly chosen near?

  • ACutoff only
  • BSaturation only
  • CThe middle of the DC load line
  • DZero collector current and zero VCE simultaneously
Report an error
Correct Answer: C. The middle of the DC load line
Explanation: Biasing near the center of the DC load line allows approximately equal signal swing toward cutoff and saturation.
Reference: Standard analog electronics: Q-point selection
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Question 53
Electronic Devices & CircuitsFET & MOSFET

For a JFET, transconductance gm represents the small-signal ratio of change in?

  • ADrain current to gate-source voltage
  • BGate current to drain-source voltage
  • CDrain voltage to source current
  • DGate voltage to gate current only
Report an error
Correct Answer: A. Drain current to gate-source voltage
Explanation: JFET transconductance is gm = dID/dVGS at the operating point, describing how effectively gate voltage controls drain current.
Reference: Standard electronics: FET transconductance
Question 54
Electronic Devices & CircuitsFeedback Amplifiers

Negative feedback in an amplifier generally tends to?

  • AIncrease gain sensitivity to device variations
  • BReduce bandwidth
  • CImprove gain stability and increase bandwidth
  • DForce the amplifier into saturation
Report an error
Correct Answer: C. Improve gain stability and increase bandwidth
Explanation: Negative feedback normally reduces closed-loop gain but improves stability, linearity and bandwidth.
Reference: Standard analog electronics: negative feedback
Question 57
Electronic Devices & CircuitsFET & MOSFET

In the ideal square-law saturation model of an enhancement nMOSFET, drain current is primarily proportional to?

  • AVGS only
  • B(VGS - VTH)^2
  • C1/VGS
  • DVDS^2 regardless of VGS
Report an error
Correct Answer: B. (VGS - VTH)^2
Explanation: In the long-channel ideal saturation model, ID is proportional to the square of the overdrive voltage VGS - VTH, neglecting channel-length modulation.
Reference: Standard electronics: MOSFET square-law model
Question 58
Electronic Devices & CircuitsOscillators

For sustained sinusoidal oscillations, the Barkhausen criterion requires the loop-gain magnitude to be approximately unity and the net loop phase shift to be?

  • A0 degrees or an integer multiple of 360 degrees
  • B90 degrees only
  • C180 degrees only regardless of feedback sign
  • D45 degrees
Report an error
Correct Answer: A. 0 degrees or an integer multiple of 360 degrees
Explanation: At the oscillation frequency, the loop must provide positive regenerative feedback: |A beta| ≈ 1 and total loop phase shift 0 degrees modulo 360 degrees.
Reference: Standard analog electronics: Barkhausen criterion
Question 59
Electronic Devices & CircuitsFET & MOSFET

For an n-channel enhancement MOSFET to be in the ideal saturation region, a common long-channel condition is?

  • AVGS < VTH
  • BVGS > VTH and VDS >= VGS - VTH
  • CVDS = 0 for all VGS
  • DVGS = 0 and VDS < 0 only
Report an error
Correct Answer: B. VGS > VTH and VDS >= VGS - VTH
Explanation: For the standard long-channel model, the device is on when VGS > VTH and enters saturation when VDS is at least the overdrive voltage VGS - VTH.
Reference: Standard electronics: MOSFET operating regions
Question 60
Electronic Devices & CircuitsOscillators

An RC phase-shift oscillator using an inverting amplifier commonly obtains approximately how much phase shift from its RC feedback network at the oscillation frequency?

  • A0 degrees
  • B90 degrees
  • C180 degrees
  • D360 degrees from each RC section
Report an error
Correct Answer: C. 180 degrees
Explanation: The inverting amplifier contributes about 180 degrees, while the RC network contributes another 180 degrees so the total loop phase shift is 360 degrees.
Reference: Standard analog electronics: RC phase-shift oscillator
Question 61
Electronic Devices & CircuitsOscillators

A Wien-bridge oscillator is widely used for generating?

  • ALow-distortion sinusoidal signals
  • BOnly square waves
  • COnly digital clock pulses above microwave frequencies
  • DDC voltage without feedback
Report an error
Correct Answer: A. Low-distortion sinusoidal signals
Explanation: The Wien-bridge oscillator is a common audio/low-frequency sine-wave oscillator capable of low distortion with suitable amplitude stabilization.
Reference: Standard analog electronics: Wien-bridge oscillator
Question 64
Electronic Devices & CircuitsOperational Amplifiers

CMRR of an operational amplifier measures its ability to?

  • AAmplify common-mode signals strongly
  • BReject common-mode signals relative to differential signals
  • CGenerate clock pulses
  • DIncrease output resistance
Report an error
Correct Answer: B. Reject common-mode signals relative to differential signals
Explanation: Common-mode rejection ratio compares differential gain with common-mode gain; a high CMRR indicates strong rejection of signals common to both inputs.
Reference: Standard analog electronics: op-amp CMRR
Question 66
Electronic Devices & CircuitsOperational Amplifiers

Slew rate of an op-amp specifies the maximum?

  • ADC input resistance
  • BRate of change of output voltage with time
  • CClosed-loop gain
  • DPower-supply voltage
Report an error
Correct Answer: B. Rate of change of output voltage with time
Explanation: Slew rate is the maximum large-signal rate at which the op-amp output voltage can change, commonly expressed in V/microsecond.
Reference: Standard analog electronics: slew rate
Question 67
Electronic Devices & CircuitsOperational Amplifiers

An op-amp has a slew rate of 0.5 V/microsecond. Approximately what minimum time is required for its output to change by 10 V at the maximum slew rate?

  • A0.05 microsecond
  • B5 microseconds
  • C20 microseconds
  • D50 microseconds
Report an error
Correct Answer: C. 20 microseconds
Explanation: Time = voltage change / slew rate = 10 V / (0.5 V/microsecond) = 20 microseconds.
Reference: Standard analog electronics: slew-rate calculation
Question 69
Electronic Devices & CircuitsOperational Amplifiers

For a single-pole internally compensated op-amp, the gain-bandwidth product is approximately?

  • AConstant over a useful closed-loop gain range
  • BAlways zero
  • CEqual to the supply voltage
  • DIndependent of frequency only at DC
Report an error
Correct Answer: A. Constant over a useful closed-loop gain range
Explanation: For a dominant-pole compensated op-amp, closed-loop gain multiplied by bandwidth is approximately constant over the usual operating range.
Reference: Standard analog electronics: gain-bandwidth product
Question 70
Electronic Devices & CircuitsBJT Amplifiers

In a common-emitter amplifier, bypassing the emitter resistor with a sufficiently large capacitor generally causes the midband voltage gain magnitude to?

  • ADecrease substantially
  • BIncrease
  • CBecome exactly zero
  • DBecome independent of transistor parameters in all cases
Report an error
Correct Answer: B. Increase
Explanation: At signal frequencies where the capacitor effectively bypasses the emitter resistor, emitter degeneration is reduced, so the voltage-gain magnitude generally increases.
Reference: Standard analog electronics: emitter bypass capacitor
Question 72
Electronic Devices & CircuitsBJT Amplifiers

A transistor amplifier has voltage gain Av = -50. The negative sign indicates?

  • APower loss only
  • BA 180-degree phase inversion between input and output voltage
  • CThe transistor is necessarily in cutoff
  • DThe output frequency is negative
Report an error
Correct Answer: B. A 180-degree phase inversion between input and output voltage
Explanation: A negative voltage gain indicates that the output voltage is inverted relative to the input, corresponding to approximately 180 degrees phase difference.
Reference: Standard analog electronics: amplifier phase inversion
Question 73
Electronic Devices & CircuitsOperational Amplifiers

For an ideal op-amp comparator with V+ greater than V-, the output tends toward?

  • AThe positive saturation level
  • BThe negative saturation level
  • CExactly zero in all cases
  • DThe input common-mode voltage
Report an error
Correct Answer: A. The positive saturation level
Explanation: With no linear negative feedback, an ideal comparator drives its output toward positive saturation when the non-inverting input exceeds the inverting input.
Reference: Standard analog electronics: comparator
Question 75
Electronic Devices & CircuitsOperational Amplifiers

A Schmitt trigger is especially useful because its hysteresis?

  • ACreates two switching thresholds and improves noise immunity
  • BMakes input resistance zero
  • CEliminates all propagation delay
  • DConverts every input directly to a sine wave
Report an error
Correct Answer: A. Creates two switching thresholds and improves noise immunity
Explanation: Hysteresis provides different thresholds for rising and falling inputs, reducing unwanted switching caused by noise near a single threshold.
Reference: Standard electronics: Schmitt trigger
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Question 76
Electronic Devices & CircuitsPower Amplifiers

The maximum theoretical collector efficiency of an ideal resistively loaded class-A power amplifier is approximately?

  • A25%
  • B50%
  • C78.5%
  • D100%
Report an error
Correct Answer: A. 25%
Explanation: For a conventional series-fed resistive class-A power amplifier, the maximum theoretical collector efficiency is 25%. Transformer-coupled class-A operation can ideally reach 50%.
Reference: Standard power electronics: class-A amplifier efficiency
Question 80
Electronic Devices & CircuitsClippers & Clampers

In a positive biased diode clipper, the clipping level is primarily determined by?

  • AOnly the input frequency
  • BThe bias voltage together with the diode forward drop
  • COnly the load resistance
  • DThe transistor beta
Report an error
Correct Answer: B. The bias voltage together with the diode forward drop
Explanation: In a biased clipper, conduction begins when the input reaches a level set by the DC bias plus or minus the diode forward drop, depending on circuit orientation.
Reference: Standard wave-shaping circuits: biased clipper
Question 81
Electronic Devices & CircuitsClippers & Clampers

An ideal clamper circuit is primarily used to?

  • AChange the DC level of a waveform without ideally changing its peak-to-peak value
  • BAmplify power by a factor of 100
  • CConvert every sine wave into DC
  • DIncrease frequency
Report an error
Correct Answer: A. Change the DC level of a waveform without ideally changing its peak-to-peak value
Explanation: A clamper shifts a waveform vertically by adding a DC component while ideally retaining the waveform shape and peak-to-peak amplitude.
Reference: Standard wave-shaping circuits: clampers
Question 82
Electronic Devices & CircuitsRectifiers & Filters

In a capacitor-input rectifier filter, increasing the load resistance while other parameters remain fixed generally causes ripple voltage to?

  • AIncrease
  • BDecrease
  • CRemain exactly unchanged
  • DBecome equal to the supply voltage
Report an error
Correct Answer: B. Decrease
Explanation: A larger load resistance reduces load current and slows capacitor discharge between charging peaks, thereby reducing ripple.
Reference: Standard electronics: capacitor-filter ripple
Question 83
Electronic Devices & CircuitsRectifiers & Filters

For a full-wave rectifier with a capacitor filter, increasing the filter capacitance while load and frequency remain fixed generally causes ripple to?

  • AIncrease
  • BDecrease
  • CBecome independent of load current
  • DDouble exactly
Report an error
Correct Answer: B. Decrease
Explanation: A larger capacitance stores more charge and its voltage falls less between rectified peaks, reducing ripple.
Reference: Standard electronics: rectifier filtering
Question 87
Electronic Devices & CircuitsBJT Biasing

Thermal runaway in a BJT refers to a potentially destructive process in which?

  • AIncreasing temperature can increase collector current and power dissipation, causing further heating
  • BThe transistor temperature always falls as current rises
  • CBase current becomes exactly zero at all temperatures
  • DThe collector-emitter voltage becomes an AC waveform only
Report an error
Correct Answer: A. Increasing temperature can increase collector current and power dissipation, causing further heating
Explanation: Temperature-dependent increases in leakage/current can raise power dissipation, causing additional heating and potentially a regenerative failure process if bias is not stabilized.
Reference: Standard transistor electronics: thermal stability
Question 88
Electronic Devices & CircuitsBJT Biasing

Which BJT bias arrangement is generally more stable against beta variation than simple fixed-base bias?

  • AVoltage-divider bias with emitter resistance
  • BFixed-base bias with no emitter resistor
  • CCollector left open
  • DBase and collector both grounded
Report an error
Correct Answer: A. Voltage-divider bias with emitter resistance
Explanation: Voltage-divider bias combined with emitter feedback makes the operating point less dependent on transistor beta than simple fixed-base bias.
Reference: Standard analog electronics: voltage-divider bias
Question 90
Electronic Devices & CircuitsPower Amplifiers

Crossover distortion in a class-B push-pull amplifier occurs mainly near?

  • AThe zero crossing of the output waveform
  • BThe positive supply rail only
  • CThe highest input frequency only
  • DDC cutoff frequency only
Report an error
Correct Answer: A. The zero crossing of the output waveform
Explanation: Near zero crossing, neither transistor may conduct until the input exceeds the required base-emitter threshold, producing a dead zone and crossover distortion.
Reference: Standard analog electronics: class-B crossover distortion
Question 91
Electronic Devices & CircuitsPower Amplifiers

Class-AB operation is commonly used instead of pure class-B operation primarily to?

  • AReduce crossover distortion
  • BEliminate all power dissipation
  • CMake voltage gain exactly zero
  • DOperate both devices permanently in cutoff
Report an error
Correct Answer: A. Reduce crossover distortion
Explanation: Class-AB biases the output devices slightly on around zero crossing, substantially reducing crossover distortion while retaining better efficiency than class A.
Reference: Standard analog electronics: class-AB amplifier
Question 92
Electronic Devices & CircuitsFET & MOSFET

A common-source FET amplifier normally produces approximately what phase relationship between input and output voltage?

  • A0 degrees
  • B90 degrees
  • C180 degrees
  • D270 degrees only
Report an error
Correct Answer: C. 180 degrees
Explanation: Like the BJT common-emitter stage, the common-source FET voltage amplifier is inverting and produces approximately 180 degrees phase reversal.
Reference: Standard FET amplifiers: common-source stage
Question 93
Electronic Devices & CircuitsFET & MOSFET

A source follower is analogous to which BJT configuration?

  • ACommon emitter
  • BCommon base
  • CEmitter follower
  • DDifferential pair only
Report an error
Correct Answer: C. Emitter follower
Explanation: The common-drain FET stage, called a source follower, has behavior analogous to the BJT common-collector or emitter-follower stage.
Reference: Standard FET amplifiers: source follower
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