Get premium membership and access questions with answers, video lessons as well as revision papers.

Show an OP-Amp with Negative Feedback

Show an OP-Amp with Negative Feedback

Answers

- An OP-amp is almost always operated with negative feedback i.e., a part of the output is fed back in phase opposition to the input (See Fig. 7.45).


- The reason is simple. The open-loop voltage gain of an OP-amp is very high (usually greater than 100,000).
- Therefore, an extremely small input voltage drives the OP-amp into its saturated output stage. For example, assume v_in = 1mV and A_OL = 100,000. Then, v_out = A_OL v_in = (100,000) × (1 mV) = 100 V
- Since the output level of an OP-amp can never reach 100 V, it is driven deep into saturation and the device becomes non-linear. With negative feedback, the voltage gain (A_CL) can be reduced and controlled so that OP-amp can function as a linear amplifier. In addition to providing a controlled and stable gain, negative feedback also provides for control of the input and output impedances and amplifier bandwidth. The table below shows the general effects of negative feedback on the performance of OP-amps.

---

Wilfykil answered the question on August 16, 2019 at 09:17

Next: What is the Frequency Response of an OP-Amp?
Previous: The diagram below shows some properties of nuclear radiations.

View More Electronics Questions and Answers | Return to Questions Index

Related Questions

• What is the Frequency Response of an OP-Amp?(Solved)
  

  What is the Frequency Response of an OP-Amp?

  Date posted: August 16, 2019.  Answers (1)

• The amplifier in Fig. 7.44 is being used to amplify an input signal to a peak output voltage of 100 mV. What is the maximum...(Solved)
  

  The amplifier in Fig. 7.44 is being used to amplify an input signal to a peak output voltage of 100 mV. What is the maximum operating frequency of the amplifier?
  
  

  Date posted: August 16, 2019.  Answers (1)

• Determine the maximum operating frequency for the circuit shown in Fig. 7.44. The slew rate is 0.5 V/µs.(Solved)
  

  Determine the maximum operating frequency for the circuit shown in Fig. 7.44. The slew rate is 0.5 V/μs.
  
  

  Date posted: August 16, 2019.  Answers (1)

• What is the definition of Slew Rate?(Solved)
  

  What is the definition of Slew Rate?

  Date posted: August 16, 2019.  Answers (1)

• An OP-amp has a gain-bandwidth product of 1.5 MHz. (Solved)
  

  An OP-amp has a gain-bandwidth product of 1.5 MHz. Find the operating bandwidth for the following closed-loop gains (i) A_CL = 1 (ii) A_CL = 10 (iii) A_CL = 100.

  Date posted: August 16, 2019.  Answers (1)

• An OP-amp has a gain-bandwidth product of 15 MHz. Determine the bandwidth of OP- amp when A_CL = 500. Also find the maximum value of...(Solved)
  

  An OP-amp has a gain-bandwidth product of 15 MHz. Determine the bandwidth of OP- amp when A_CL = 500. Also find the maximum value of A_CL when f₂ = 200 kHz.

  Date posted: August 16, 2019.  Answers (1)

• Explain the Output Voltage from OP-Amp(Solved)
  

  Explain the Output Voltage from OP-Amp

  Date posted: August 16, 2019.  Answers (1)

• Show the schematic symbol of an operational amplifier(Solved)
  

  Show the schematic symbol of an operational amplifier

  Date posted: August 16, 2019.  Answers (1)

• The differential amplifier shown in Fig. 7.14 has a differential voltage gain of 2500 and a CMRR of 30,000.(Solved)
  

  The differential amplifier shown in Fig. 7.14 has a differential voltage gain of 2500 and a CMRR of 30,000. A single-ended input signal of 500 μV r.m.s. is applied. At the same time, 1V, 50 Hz interference signal appears on both inputs as a result of radiated pick-up from the a.c. power system.
  (i) Determine the common-mode gain.
  (ii) Express the CMRR in dB.
  (iii) Determine the r.m.s. output signal.
  (iv) Determine the r.m.s. interference voltage on the output.
  
  

  Date posted: August 15, 2019.  Answers (1)

• A differential amplifier has a voltage gain of 150 and a CMRR of 90 dB.(Solved)
  

  A differential amplifier has a voltage gain of 150 and a CMRR of 90 dB. The input signals are 50 mV and 100 mV with 1 mV of noise on each input. Find (i) the output signal (ii) the noise on the output.

  Date posted: August 15, 2019.  Answers (1)

• A differential amplifier has an output of 1V with a differential input of 10 mV and an output of 5 mV with a common-mode input...(Solved)
  

  A differential amplifier has an output of 1V with a differential input of 10 mV and an output of 5 mV with a common-mode input of 10 mV. Find the CMRR in dB.

  Date posted: August 15, 2019.  Answers (1)

• A certain differential amplifier has a differential voltage gain of 2000 and a common mode gain of 0.2. Determine CMRR and express it in dB.(Solved)
  

  A certain differential amplifier has a differential voltage gain of 2000 and a common mode gain of 0.2. Determine CMRR and express it in dB.

  Date posted: August 15, 2019.  Answers (1)

• Discuss the Voltage Gains of DA(Solved)
  

  Discuss the Voltage Gains of DA

  Date posted: August 15, 2019.  Answers (1)

• Discuss the Double-ended Input Operation of DA(Solved)
  

  Discuss the Double-ended Input Operation of DA

  Date posted: August 15, 2019.  Answers (1)

• Explain the Common-mode and Differential-mode Signals(Solved)
  

  Explain the Common-mode and Differential-mode Signals

  Date posted: August 15, 2019.  Answers (1)

• Explain the Basic Circuit of Differential Amplifier(Solved)
  

  Explain the Basic Circuit of Differential Amplifier

  Date posted: August 15, 2019.  Answers (1)

• differential amplifier has an open-circuit voltage gain of 100. The input signals are 3.25 V and 3.15V. Determine the output voltage.(Solved)
  

  differential amplifier has an open-circuit voltage gain of 100. The input signals are 3.25 V and 3.15V. Determine the output voltage.

  Date posted: August 15, 2019.  Answers (1)

• What is a Differential Amplifier (DA)?(Solved)
  

  What is a Differential Amplifier (DA)?

  Date posted: August 15, 2019.  Answers (1)

• Define what an Operational Amplifier is(Solved)
  

  Define what an Operational Amplifier is

  Date posted: August 15, 2019.  Answers (1)

• What are the Limitations of LC and RC Oscillators?(Solved)
  

  What are the Limitations of LC and RC Oscillators?

  Date posted: August 15, 2019.  Answers (1)