What is the typical open-loop gain of an operational amplifier?
A 10
B 100
C 1,000
D 100,000 or more
Operational amplifiers have a very high open-loop gain (typically 100,000 or more) to amplify even the weakest input signals.
What is the effect of increasing the load resistance in a rectifier circuit?
A Output voltage decreases
B Ripple factor increases
C Ripple factor decreases
D Efficiency decreases
Increasing the load resistance decreases the current drawn, reducing the ripple factor and producing a smoother output.
Which of the following is a voltage-controlled current device?
A BJT
B MOSFET
C Diode
D Resistor
MOSFETs are voltage-controlled current devices, meaning the current flowing through the device is controlled by the voltage applied to the gate terminal.
What does SPICE simulation primarily analyze?
A Circuit layout
B Analog circuit behavior
C Thermal stability
D Fabrication process
SPICE (Simulation Program with Integrated Circuit Emphasis) simulates the electrical behavior of analog and mixed-signal circuits.
What is the role of a heat sink in power amplifiers?
A To amplify power
B To stabilize voltage
C To dissipate heat
D To filter noise
Heat sinks are used to dissipate the heat generated by power amplifiers, preventing thermal runaway and ensuring reliability.
Which terminal of a transistor controls the flow of current between the other two terminals?
A Base
B Collector
C Emitter
D Gate
In a Bipolar Junction Transistor (BJT), the base terminal controls the current flow between the collector and emitter. A small base current controls a larger current through the collector-emitter path.
What is the main function of a Zener diode?
A Signal amplification
B Voltage regulation
C Current rectification
D Frequency filtering
A Zener diode operates in reverse bias in the breakdown region, maintaining a constant output voltage despite variations in the input voltage or load.
Which transistor configuration provides the lowest output impedance?
A Common Base
B Common Emitter
C Common Collector
D Darlington Pair
The common collector configuration, also called an emitter follower, provides low output impedance, making it ideal for impedance matching.
What is the main advantage of a Field Effect Transistor (FET) over a Bipolar Junction Transistor (BJT)?
A Higher current gain
B Higher input impedance
C Better thermal stability
D Lower output impedance
FETs have very high input impedance because their gate terminal is insulated from the channel, making them ideal for applications requiring minimal loading of the input signal.
Which type of diode is used in rectifier circuits?
A Schottky diode
B LED
C PN junction diode
D Tunnel diode
PN junction diodes are used in rectifier circuits because they allow current to flow in one direction and block it in the opposite direction, converting AC to DC.
What is the typical value of the voltage drop across a germanium diode in forward bias?
A 0.3 V
B 0.7 V
C 1.1 V
D 0 V
Germanium diodes have a lower forward voltage drop of about 0.3 V, compared to silicon diodes with a typical drop of 0.7 V.
Which of the following is a unipolar device?
A FET
B BJT
C SCR
D Diode
Field Effect Transistors (FETs) are unipolar devices because they operate using only one type of charge carrier (either electrons or holes), unlike BJTs, which use both.
What is the function of an emitter bypass capacitor in a common emitter amplifier?
A To stabilize DC voltage
B To increase AC gain
C To block AC signals
D To reduce input impedance
The emitter bypass capacitor shorts AC signals to ground, preventing AC signal loss across the emitter resistor, thereby increasing the AC gain.
What does the term “slew rate” refer to in an op-amp?
A The maximum rate of change of the output voltage
B The maximum input voltage
C The gain-bandwidth product
D The noise level
Slew rate specifies the maximum rate at which an op-amp can change its output voltage, typically measured in volts per microsecond (V/μs).
Which amplifier class has the highest efficiency?
A Class A
B Class B
C Class AB
D Class D
Class D amplifiers, also known as digital amplifiers, are highly efficient (up to 90% or more) because they operate using switching techniques that minimize power loss.
In a BJT, which region is reverse-biased during normal active operation?
A Base-Emitter junction
B Base-Collector junction
C Emitter-Collector junction
D All junctions
In active mode, the base-emitter junction of a BJT is forward-biased, and the base-collector junction is reverse-biased, enabling amplification.
What type of circuit is used to produce a square wave from a sinusoidal input?
A Integrator
B Differentiator
C Schmitt Trigger
D Voltage regulator
A Schmitt Trigger converts a sinusoidal input into a square wave by using hysteresis to define distinct switching points.
What is the role of a coupling capacitor in amplifier circuits?
A To stabilize the circuit
B To block DC while allowing AC signals to pass
C To amplify the signal
D To match impedance
Coupling capacitors are used to separate AC signals from DC bias components, enabling the signal to pass between stages without altering the DC operating point.
What is the function of a voltage regulator IC like 7805?
A To provide variable voltage
B To provide a fixed +5 V output
C To amplify current
D To filter noise
The 7805 is a fixed voltage regulator IC that provides a stable +5 V output regardless of variations in input voltage or load.
Which type of amplifier is used to amplify low-level differential signals?
A Differential amplifier
B Common emitter amplifier
C Voltage follower
D Power amplifier
Differential amplifiers amplify the difference between two input signals, rejecting common-mode signals such as noise.
Which of the following is an example of a passive component?
A Transistor
B Diode
C Resistor
D Operational Amplifier
Passive components do not require any external power to operate. A resistor is a passive component, while transistors, diodes, and op-amps are active components.
What is the primary purpose of a power amplifier?
A To amplify weak signals
B To provide high power to the load
C To filter noise from signals
D To stabilize input voltage
Power amplifiers are designed to drive loads such as speakers by providing sufficient power, rather than amplifying weak input signals.
Which material is commonly used for making LEDs?
A Silicon
B Germanium
C Gallium arsenide
D Carbon
LEDs are typically made from semiconductors like gallium arsenide or gallium phosphide, which emit light when current flows through them.
What is the function of the base-emitter junction in a BJT?
A Acts as a current source
B Controls the collector current
C Blocks current flow
D Regulates voltage
In a BJT, the base-emitter junction is forward-biased, allowing a small base current to control a much larger collector current.
Which of the following is used to stabilize an amplifier’s gain?
A Positive feedback
B Negative feedback
C Coupling capacitor
D Voltage divider
Negative feedback reduces distortion and stabilizes the gain of an amplifier by feeding a portion of the output back to the input in the opposite phase.
What is the output waveform of a full-wave rectifier for a sinusoidal input?
A Pure DC
B Pulsating DC
C Sine wave
D Square wave
A full-wave rectifier converts both halves of an AC signal into pulsating DC. The output still contains ripples and requires filtering to achieve pure DC.
What is the typical forward voltage drop of a Schottky diode?
A 0.3 V
B 0.7 V
C 1.1 V
D 0 V
Schottky diodes have a low forward voltage drop (approximately 0.3 V) compared to silicon diodes (0.7 V), making them suitable for high-speed switching applications.
What is the primary function of an operational amplifier in an integrator circuit?
A To multiply signals
B To calculate the derivative of the input
C To calculate the integral of the input
D To generate oscillations
In an integrator circuit, the op-amp produces an output voltage proportional to the integral of the input signal over time.
Which type of biasing provides the most stable Q-point in a transistor circuit?
A Fixed bias
B Collector-to-base bias
C Voltage-divider bias
D Emitter bias
Voltage-divider bias is widely used because it stabilizes the Q-point against variations in transistor beta (β) and temperature changes.
Which parameter of a filter defines its ability to differentiate between the passband and the stopband?
A Bandwidth
B Roll-off rate
C Cut-off frequency
D Impedance
The roll-off rate determines how sharply a filter transitions between the passband and stopband. Higher roll-off rates result in better selectivity.
What is the purpose of a decoupling capacitor in an electronic circuit?
A To block AC signals
B To amplify signals
C To stabilize voltage by filtering noise
D To increase impedance
Decoupling capacitors are used to filter out high-frequency noise from the power supply, ensuring stable operation of sensitive components.
What type of amplifier operates for less than 360 degrees but more than 180 degrees of the input signal cycle?
A Class A
B Class B
C Class AB
D Class C
Class AB amplifiers conduct for slightly more than half (180 degrees) but less than the full cycle (360 degrees), combining the advantages of Class A and Class B operation.
What is the purpose of a tank circuit in an oscillator?
A To provide feedback
B To store energy and determine frequency
C To amplify signals
D To reduce distortion
A tank circuit consists of an inductor and a capacitor, which store energy and oscillate at a natural resonant frequency to determine the output frequency of the oscillator.
Which parameter represents the efficiency of a rectifier?
A Ripple factor
B Peak inverse voltage
C Conversion efficiency
D Regulation ratio
The efficiency of a rectifier is the ratio of DC power delivered to the load to the AC power input, expressed as a percentage.
What is the typical bandwidth of a low-pass filter?
A The range of frequencies below the cut-off frequency
B The range of frequencies above the cut-off frequency
C All frequencies
D None of the above
A low-pass filter allows frequencies below its cut-off frequency to pass while attenuating higher frequencies.
What is the primary purpose of a differential amplifier?
A Amplify DC signals
B Amplify the difference between two input signals
C Block noise signals
D Amplify both input signals equally
A differential amplifier amplifies the voltage difference between two input signals, making it effective for rejecting common-mode noise and interference.
What type of signal is analyzed in small-signal analysis?
A High-frequency signal
B Low-frequency signal
C Large amplitude signal
D Small amplitude signal
Small-signal analysis focuses on linearizing and analyzing the behavior of a circuit for small amplitude signals around a bias point.
Which parameter of an amplifier represents the maximum frequency it can handle effectively?
A Bandwidth
B Slew rate
C Frequency response
D Gain
Bandwidth is the range of frequencies over which an amplifier can operate effectively with minimal signal attenuation.
What is the role of a gain-bandwidth product (GBP) in an amplifier?
A To define noise immunity
B To measure stability
C To define the trade-off between gain and bandwidth
D To increase power efficiency
The gain-bandwidth product is constant for an amplifier, meaning that increasing gain reduces bandwidth, and vice versa.
Which class of power amplifiers operates for the entire 360° of the input cycle?
A Class A
B Class B
C Class AB
D Class C
Class A amplifiers conduct for the full 360° of the input signal cycle, ensuring high fidelity but lower efficiency compared to other classes.
What is the purpose of a waveform generator?
A To filter signals
B To produce specific waveforms like sine, square, and triangle waves
C To rectify AC signals
D To amplify low signals
Waveform generators are used in testing and designing circuits by providing various periodic signals with adjustable parameters.
What is the most common cause of harmonic distortion in amplifiers?
A Operating in the linear region
B Nonlinear behavior of components
C Low-frequency signals
D Thermal noise
Harmonic distortion arises when amplifiers operate in nonlinear regions, producing harmonics of the input signal.
What is the function of a filter in a signal conditioning circuit?
A Amplify signals
B Block specific frequencies while allowing others
C Convert AC to DC
D Generate waveforms
Filters selectively allow or block specific frequency ranges to shape the signal as required, such as removing noise or isolating a desired frequency band.
What type of distortion is caused by the overlapping of two frequencies in a circuit?
A Harmonic distortion
B Crossover distortion
C Intermodulation distortion
D Frequency distortion
Intermodulation distortion occurs when two or more frequencies mix in a nonlinear system, producing unwanted signals at other frequencies.
What is the effect of increasing capacitance in a low-pass RC filter?
A Increases the cut-off frequency
B Decreases the cut-off frequency
C Has no effect on the cut-off frequency
D Increases gain
In an RC low-pass filter, the cut-off frequency is inversely proportional to capacitance. Increasing capacitance lowers the cut-off frequency, allowing only lower frequencies to pass.
Which type of feedback is used in an oscillator circuit?
A Positive feedback
B Negative feedback
C Current feedback
D Voltage feedback
Positive feedback is essential in oscillators to sustain oscillations by reinforcing the signal’s amplitude at the input.
What is the purpose of a decoupling capacitor in a circuit?
A To store energy
B To filter out noise
C To pass DC signals
D To increase gain
Decoupling capacitors are used to filter out high-frequency noise from power supply lines, stabilizing the voltage for sensitive components.
What is the output waveform of a half-wave rectifier?
A Pure DC
B Pulsating DC with one polarity
C Alternating AC
D Pulsating DC with both polarities
A half-wave rectifier removes one-half of the AC cycle, leaving a pulsating DC signal with only one polarity.
What is the role of a filter in a power supply circuit?
A To convert AC to DC
B To remove ripples from the rectified signal
C To increase the frequency of the signal
D To amplify the signal
Filters smooth out the pulsating DC output of a rectifier, reducing ripples to produce a steady DC voltage.
What is the main purpose of a voltage divider bias in a transistor circuit?
A To increase voltage gain
B To stabilize the operating point
C To amplify current
D To switch the transistor ON and OFF
Voltage divider bias is used to set and stabilize the operating point of a transistor, ensuring consistent performance despite temperature or beta variations.