What is the primary function of a power amplifier?
A Voltage regulation
B Signal amplification
C Signal rectification
D Signal filtering
A power amplifier is used to increase the power of a signal. It amplifies the input signal to a level that is strong enough to drive loads such as speakers, motors, or other power-dependent devices.
In a differential amplifier, what is amplified?
A Voltage difference
B Power difference
C Current difference
D Frequency difference
A differential amplifier amplifies the voltage difference between two input signals. It is used in applications where the difference in signals is important, such as in instrumentation or sensor applications.
What does small-signal analysis primarily focus on in an amplifier circuit?
A Nonlinear behavior
B Large voltage swings
C High-frequency behavior
D Linear approximation
Small-signal analysis focuses on the linear behavior of an amplifier circuit when the input signal is small enough that the nonlinearities of the device can be approximated as linear. This helps in understanding the amplifier’s performance in its linear operating range.
In a power amplifier, what is the main goal?
A Signal amplification
B Frequency conversion
C High power output
D Voltage regulation
The primary goal of a power amplifier is to increase the power of an input signal to a level that can drive large loads, like speakers, by providing high output power while maintaining signal fidelity.
What defines the gain of a differential amplifier?
A Voltage gain
B Current gain
C Power gain
D Current regulation
The gain of a differential amplifier is defined by the ratio of the output voltage to the input voltage difference. It is designed to amplify the voltage difference between two inputs while rejecting common-mode signals.
What is the role of a biasing network in a small-signal amplifier?
A Amplify input
B Set operating point
C Increase gain
D Filter noise
The biasing network in a small-signal amplifier sets the operating point of the active device (like a transistor or FET) to ensure that the amplifier operates in its linear region, providing reliable amplification without distortion.
Which type of amplifier configuration has the highest voltage gain?
A Common-base
B Differential
C Common-emitter
D Common-collector
The common-emitter amplifier configuration provides the highest voltage gain. It is widely used for voltage amplification in analog circuits due to its high gain and versatility in various applications.
What happens to the input signal in a differential amplifier?
A Amplified only
B Inverted
C Amplified and subtracted
D Amplified and added
In a differential amplifier, the two input signals are processed so that their difference is amplified; in many designs the signals are effectively added (with one inverted) to yield the output.
In small-signal analysis, what assumption is made about the input signal?
A The signal is nonlinear
B The signal is large
C The signal is small
D The signal is sinusoidal
Small-signal analysis assumes that the input signal is small enough that the behavior of the circuit can be approximated as linear. This allows the use of simplified models for accurate analysis of the circuit’s performance.
What type of distortion is most common in power amplifiers?
A Harmonic distortion
B Amplitude distortion
C Frequency distortion
D Phase distortion
Harmonic distortion is common in power amplifiers when the amplifier introduces additional harmonics to the output signal. This is due to the nonlinearities in the amplification process, affecting the purity of the amplified signal.
What is the primary advantage of a differential amplifier over a single-ended amplifier?
A Higher voltage gain
B Better noise rejection
C Higher power consumption
D Simpler design
A differential amplifier offers better noise rejection because it amplifies only the difference between two input signals, rejecting common-mode noise that may be present on both inputs. This makes it ideal for noise-sensitive applications.
In small-signal analysis, which model is commonly used to approximate the behavior of a transistor?
A Ideal model
B Thevenin model
C Hybrid-pi model
D Norton model
The hybrid-pi model is commonly used in small-signal analysis of transistors. It represents the transistor’s behavior using resistors, capacitors, and dependent sources, providing an accurate approximation of the transistor’s response to small variations in input.
What is the typical use of a class AB power amplifier?
A Digital switching
B Signal modulation
C Audio amplification
D Signal filtering
Class AB power amplifiers are commonly used in audio amplification because they combine the efficiency of class B amplifiers with the low distortion of class A amplifiers. This makes them suitable for high-quality audio applications.
In a differential amplifier, what does the common-mode rejection ratio (CMRR) indicate?
A Noise rejection
B Frequency response
C Voltage gain
D Signal strength
The common-mode rejection ratio (CMRR) indicates how well a differential amplifier rejects common-mode signals, such as noise or interference. A higher CMRR means the amplifier can more effectively reject unwanted signals and focus on the differential input.
What is the main feature of a class A power amplifier?
A Low distortion
B High power output
C High linearity
D High efficiency
Class A power amplifiers are known for their high linearity, which results in low distortion. They operate by keeping the active device (such as a transistor) in conduction for the entire input cycle, ensuring a faithful amplification of the input signal.