Trusted since 2008
LoginRegister
Study resources on Kenyaplex

Get ready-made curriculum aligned revision materials

Exam papers, notes, holiday assignments and topical questions – all aligned to the Kenyan curriculum.

Browse exam papers
Or go directly to:
Class notes Holiday assignments Topical questions Other resources

Explain the Common-mode and Differential-mode Signals

Explain the Common-mode and Differential-mode Signals

Answers

Wilfred
- The importance of a differential amplifier lies in the fact that the outputs are proportional to the difference between the two input signals. Thus the circuit can be used to amplify the difference between the two input signals or amplify only one input signal simply by grounding the other input.
- The input signals to a DA are defined as:

(i) Common-mode signals: When the input signals to a DA are in phase and exactly equal in amplitude, they are called common-mode signals as shown in Fig. 7.7. The common-mode signals are rejected (not amplified) by the differential amplifier. It is because a differential amplifier amplifies the difference between the two signals (v1 – v2) and for common-mode signals, this difference is zero. Note that for common-mode operations, v1 = v2.

(ii) Differential-mode signals When the input signals to a DA are 180° out of phase and exactly equal in amplitude, they are called differential-mode signals as shown in Fig. 7.9.
The differential-mode signals are amplified by the differential amplifier. It is because the difference in the signals is twice the value of each signal. For differential-mode signals, v1 = –v2.
amp31582019411.png
- Therefore a differential amplifier will amplify the differential-mode signals while it will reject the common- mode signals.
Wilfykil answered the question on August 15, 2019 at 13:38

Answer Attachments

Next: A poultry farmer has twenty times as many hens as turkeys and three quarters as many ducks as turkeys. a) If there are t, turkeys, write...

Previous: The figure below shows a portable Kennel. a) Calculate i) The total surface area of the walls and the floor. ii) The total area of the roof....

View more Electronics Questions and Answers  |  Return to Questions Index

Exams With Marking Schemes

Related Questions