Ch 6 Op-Amp

Question 1

Q: What is an operational amplifier (Op-Amp)?

Answer 1

A: An electronic device designed to amplify voltage signals with high gain.

Question 2

Q: Define the open-loop gain of an Op-Amp.

Answer 2

A: The gain of the Op-Amp without any external feedback, typically very high (e.g., to ).

Question 2

Q: What are the two main input terminals of an Op-Amp?

Answer 2

A: Inverting input (-) and non-inverting input (+).

Question 3

Q: What is a voltage follower?

Answer 3

A: An Op-Amp configuration with unity gain where the output voltage equals the input voltage.

Question 4

Q: What is the purpose of feedback in Op-Amp circuits?

Answer 4

A: To control the gain and stability of the circuit.

Question 5

Q: Describe the inverting amplifier configuration.

Answer 5

A: An Op-Amp circuit where the input signal is applied to the inverting terminal, producing an output that is inverted and amplified.

Question 6

Q: What is the gain formula for an inverting amplifier?

Answer 6

A: , where is the feedback resistor and is the input resistor.

Question 7

Q: Describe the non-inverting amplifier configuration.

Answer 7

A: An Op-Amp circuit where the input signal is applied to the non-inverting terminal, producing an amplified output with the same phase.

Question 8

Q: What is a summing amplifier?

Answer 8

A: An Op-Amp configuration that combines multiple input signals into a single output signal.

Question 9

Q: Define a differential amplifier.

Answer 9

A: An Op-Amp circuit that amplifies the difference between two input voltages.

Question 10

Q: What is the bandwidth of an Op-Amp?

Answer 10

A: The range of frequencies over which the Op-Amp can operate effectively with a specified gain.

Question 10

Q: Define the slew rate of an Op-Amp.

Answer 10

A: The maximum rate at which the output voltage can change, typically measured in volts per microsecond (V/µs).

Question 10

Q: What is the function of a comparator circuit using an Op-Amp?

Answer 10

A: To compare two input voltages and output a high or low signal based on which input is greater.

Question 11

Q: What is the input impedance of an ideal Op-Amp?

Answer 11

A: Infinite.

Question 12

Q: What is the output impedance of an ideal Op-Amp?

Answer 12

A: Zero.

Question 13

Q: What is a practical use of an integrator circuit using an Op-Amp?

Answer 13

A: To compute the integral of an input signal, commonly used in signal processing.

Question 14

Q: What is a practical use of a differentiator circuit using an Op-Amp?

Answer 14

A: To compute the derivative of an input signal, useful in detecting rapid changes.

Question 15

Q: Why are Op-Amps often used in filters?

Answer 15

A: To design active filters with precise frequency responses, such as low-pass, high-pass, and band-pass filters.

Question 16

Q: What is common-mode rejection ratio (CMRR)?

Answer 16

A: The ability of an Op-Amp to reject common-mode signals and amplify only the differential signal.

Question 17

Q: What is the typical value of CMRR for Op-Amps?

Answer 17

A: Very high, often over 70 dB.

Question 18

Q: What is the role of offset voltage in Op-Amps?

Answer 18

A: A small voltage that may be present at the output even when the input is zero, typically corrected in precision applications.

Question 19

Q: Define virtual ground in the context of Op-Amps.

Answer 19

A: A point in the circuit that is at a fixed voltage, usually 0V, despite not being directly connected to the actual ground.

Question 20

Q: What is the difference between an ideal and a practical Op-Amp?

Answer 20

A: An ideal Op-Amp has infinite gain, infinite input impedance, zero output impedance, and no offset voltage, while practical Op-Amps have limitations in all these parameters.

Question 21

Q: Name a common Op-Amp IC.

Answer 21

A: LM741 is a widely used general-purpose Op-Amp.