Assignment - 4: Feedback Amplifiers

What is the purpose of feedback in amplifier circuits?

• To increase power consumption

• To eliminate all noise completely

• To solely amplify high frequencies

• The purpose of feedback in amplifier circuits is to control gain, improve stability, reduce distortion, and enhance bandwidth.

How do you calculate the gain of a feedback amplifier?

• Gain = Vout + Vin

• Gain = Vout / Vin or Closed-loop Gain = Open-loop Gain / (1 + Open-loop Gain * Feedback Factor)

• Closed-loop Gain = Open-loop Gain + Feedback Factor

• Gain = Vin / Vout

Identify the four main types of feedback used in amplifiers.

• Positive feedback, Negative feedback, Voltage feedback, Current feedback

• Feedback loop, Signal feedback, Phase feedback, Gain feedback

Explain the concept of stability in feedback amplifiers.

• Stability refers to the maximum gain of the amplifier.

• Stability is the speed at which the amplifier responds to input changes.

• Stability in feedback amplifiers is only concerned with power consumption.

• Stability in feedback amplifiers is the ability to maintain consistent output without oscillation, assessed through phase and gain margins.

What is the difference between negative and positive feedback?

• Negative feedback only occurs in biological systems, while positive feedback is found in mechanical systems.

• Negative feedback leads to chaos, while positive feedback leads to stability.

• Negative feedback stabilizes systems, while positive feedback enhances changes.

• Negative feedback is always harmful, while positive feedback is always beneficial.

How does feedback affect the input and output impedance of an amplifier?

• Both types of feedback increase both input and output impedance.

• Feedback affects input and output impedance by increasing input impedance and decreasing output impedance in negative feedback, while positive feedback can have the opposite effect.

• Feedback has no effect on impedance.

• Feedback only affects voltage gain, not impedance.

Describe the role of the feedback factor in amplifier design.

• The feedback factor is irrelevant in digital amplifiers.

• The feedback factor solely determines the power supply requirements.

• The feedback factor only affects the physical size of the amplifier.

• The feedback factor controls gain, stability, bandwidth, and linearity in amplifier design.

What are the advantages of using feedback in amplifier circuits?

• Limited frequency response

• Higher noise levels

• Increased power consumption

• The advantages of using feedback in amplifier circuits include stabilization of gain, reduction of distortion, improvement of bandwidth, and enhancement of linearity.

How can you determine the frequency response of a feedback amplifier?

• Analyze the circuit's DC characteristics to find the frequency response.

• Use a large-signal input to assess the amplifier's performance.

• Measure the input voltage at a single frequency only.

• Apply a small-signal input at varying frequencies and measure the output to plot the frequency response.

What is the significance of the bandwidth in feedback amplifiers?

• The bandwidth is irrelevant to the amplifier's gain.

• The bandwidth determines the frequency range over which the amplifier operates effectively.

• The bandwidth affects the power supply voltage of the amplifier.

• The bandwidth determines the physical size of the amplifier.