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All Electronics & Telecommunication MCQs

Browse Electronics & Telecommunication Engineering MCQs with four options, hidden answers, concise explanations and references where available. Questions are organized in pages of up to 100 for focused practice.

Question 101
Digital ElectronicsNumber Systems & Codes

The Gray-code equivalent of binary 1011 is?

  • A1110
  • B1010
  • C1101
  • D1001
Report an error
Correct Answer: A. 1110
Explanation: For binary-to-Gray conversion, the MSB is unchanged and each following Gray bit is the XOR of adjacent binary bits: 1, 1 XOR 0 = 1, 0 XOR 1 = 1, 1 XOR 1 = 0, giving 1110.
Reference: Standard digital electronics: Gray code conversion
Question 105
Digital ElectronicsMemory

A 4K × 8 memory has a total capacity of?

  • A4 Kbits
  • B8 Kbits
  • C32 Kbits
  • D64 Kbits
Report an error
Correct Answer: C. 32 Kbits
Explanation: There are 4096 words of 8 bits each, giving 4096 × 8 = 32768 bits = 32 Kbits.
Reference: Standard digital electronics: memory capacity
Question 107
Digital ElectronicsADC & DAC

Which ADC architecture is generally known for very high conversion speed because it uses many comparators in parallel?

  • ADual-slope ADC
  • BFlash ADC
  • CSuccessive-approximation ADC
  • DIntegrating ADC only
Report an error
Correct Answer: B. Flash ADC
Explanation: A flash ADC compares the input simultaneously against many reference levels, providing very fast conversion at the cost of many comparators.
Reference: Standard digital electronics: ADC architectures
Question 108
Digital ElectronicsADC & DAC

A successive-approximation ADC determines the digital output primarily by?

  • ATesting bits through a binary-search-like sequence
  • BCounting indefinitely until power is removed
  • CUsing only one fixed comparator threshold with no DAC
  • DDirectly storing the analog voltage as binary charge
Report an error
Correct Answer: A. Testing bits through a binary-search-like sequence
Explanation: A SAR ADC successively tests candidate bits, effectively performing a binary search using an internal DAC and comparator.
Reference: Standard digital electronics: SAR ADC
Question 109
Electronic Devices & CircuitsSemiconductor Fundamentals

In an intrinsic semiconductor at thermal equilibrium, the electron concentration n and hole concentration p are related by?

  • An > p
  • Bn < p
  • Cn = p = ni
  • Dn + p = 0
Report an error
Correct Answer: C. n = p = ni
Explanation: In an intrinsic semiconductor, thermally generated electrons and holes occur in equal numbers, so n = p = ni.
Reference: Standard semiconductor electronics: intrinsic carrier concentration
Question 110
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 111
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 112
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 113
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 114
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 115
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 116
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 117
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 121
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 125
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 126
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 127
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 128
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 129
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 130
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
Question 133
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 134
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 135
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 140
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 146
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 147
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
Question 148
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 149
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 150
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 152
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 153
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 155
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 157
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 158
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 161
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 162
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 165
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 167
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 168
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 169
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 172
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 174
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 175
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 176
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 178
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 179
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
Question 180
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 182
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 183
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 187
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 188
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 189
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 190
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 194
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 195
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 196
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 198
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 199
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 200
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