What is the main purpose of feedback in an amplifier circuit?
A Signal isolation
B Power regulation
C Signal conversion
D Stabilize gain
Feedback in amplifier circuits is used to stabilize the gain and reduce distortion. Negative feedback, in particular, ensures that the output signal is less affected by variations in input or operating conditions, improving the overall performance of the amplifier.
Which type of amplifier is used to increase both voltage and current?
A Power amplifier
B Differential amplifier
C Voltage amplifier
D Operational amplifier
A power amplifier is used to amplify both voltage and current, delivering higher output power. It is used in applications where large amounts of power are needed, such as driving speakers or transmitting radio signals.
In an oscillator circuit, what is the key requirement for sustained oscillations?
A Zero impedance
B Negative feedback
C Positive feedback
D Zero gain
Sustained oscillations in an oscillator circuit require positive feedback, where a portion of the output is fed back to the input in phase with the original signal. This maintains the oscillation at a constant amplitude and frequency.
What does a voltage regulator primarily do in an electronic circuit?
A Increase signal strength
B Maintain constant voltage
C Convert AC to DC
D Filter noise
A voltage regulator is designed to maintain a constant output voltage despite variations in input voltage or load conditions. It is critical for protecting sensitive components from voltage fluctuations and ensuring proper operation of electronic devices.
Which type of voltage regulator uses a Zener diode to stabilize voltage?
A Buck regulator
B Linear regulator
C Shunt regulator
D Switching regulator
A shunt regulator uses a Zener diode to regulate voltage. The Zener diode operates in reverse breakdown, clamping the voltage to a set value, ensuring a constant output voltage. This type of regulator is often used for low-power applications.
What type of feedback is typically used in amplifiers to improve bandwidth?
A Positive feedback
B Negative feedback
C Voltage feedback
D Current feedback
Negative feedback is used in amplifiers to improve bandwidth, reduce distortion, and increase stability. It reduces the overall gain but increases the linearity and performance of the amplifier across a wide frequency range.
In an op-amp-based oscillator, what determines the frequency of oscillation?
A Feedback network
B Load resistance
C Input voltage
D Power supply
In an op-amp-based oscillator, the frequency of oscillation is determined by the feedback network, which typically consists of resistors and capacitors. The values of these components set the timing for the oscillation cycle.
What is the primary advantage of using a switching regulator over a linear regulator?
A Simpler design
B Better efficiency
C Smaller size
D Constant voltage output
Switching regulators are more efficient than linear regulators because they use a switching element (like a transistor) to convert excess voltage into current, rather than dissipating it as heat. This results in higher efficiency, especially in high-power applications.
What type of oscillator generates a sine wave?
A Relaxation oscillator
B Colpitts oscillator
C Wien bridge oscillator
D Hartley oscillator
The Wien bridge oscillator is designed to generate a stable sine wave. It uses a bridge circuit that balances positive feedback with resistors and capacitors to maintain oscillations at a specific frequency, providing a pure sine wave output.
What is a key characteristic of a voltage-controlled oscillator (VCO)?
A Frequency modulation
B Fixed frequency
C Output amplitude control
D Frequency determined by input voltage
A voltage-controlled oscillator (VCO) has an output frequency that is determined by the input voltage. This makes VCOs ideal for applications where frequency needs to be varied dynamically, such as in communication systems and signal generators.
What type of voltage regulator is most commonly used in power supply circuits?
A Linear regulator
B Buck converter
C Zener diode regulator
D Switching regulator
Linear regulators are commonly used in power supply circuits because they provide a simple and efficient way to maintain a constant output voltage. They operate by dissipating excess energy as heat, making them suitable for low-power applications.
In a feedback amplifier, what is the role of the feedback network?
A Set output voltage
B Increase voltage gain
C Control bandwidth
D Decrease current
The feedback network in a feedback amplifier controls the bandwidth by shaping the frequency response of the circuit. By adjusting the feedback components, the amplifier’s performance can be optimized for specific frequency ranges.
Which of the following is the most common type of feedback used in op-amps?
A Voltage feedback
B Negative feedback
C Current feedback
D Positive feedback
Negative feedback is the most common type used in op-amp circuits. It stabilizes the gain, reduces distortion, and improves linearity, making it ideal for high-precision applications like amplifiers, filters, and integrators.
What is the primary function of a Hartley oscillator?
A Regulate voltage
B Amplify signals
C Generate sine waves
D Generate square waves
The Hartley oscillator is a type of LC oscillator that generates sine waves. It uses an inductive voltage divider in its feedback loop, which determines the frequency of oscillation, making it suitable for RF applications.
What happens when an op-amp is operated in an open-loop configuration?
A High gain
B Stable output
C Low bandwidth
D High gain
In an open-loop configuration, an op-amp operates with very high gain, meaning even small differences between the inputs can result in large changes in the output. However, this high gain makes the op-amp sensitive to noise and instability, limiting its practical use.