The main applications of feedback in electronics are in the designs of amplifiers, oscillators, and logic circuit elements.
The processing and control of feedback is engineered into many electronic devices and may also be embedded in other technologies.
If the signal is inverted on its way round the control loop, the system is said to have negative feedback; otherwise, the feedback is said to be positive. Negative feedback is often deliberately introduced to increase the stability and accuracy of a system by correcting unwanted changes. This scheme can fail if the input changes faster than the system can respond to it. When this happens, the lag in arrival of the correcting signal results in unintended positive feedback, causing the output to oscillate or hunt[7] Oscillation is usually an unwanted consequence of system behaviour.
Harry Nyquist contributed the Nyquist plot for assessing the stability of feedback systems. An easier assessment, but less general, is based upon gain margin and phase margin using Bode plots (contributed by Hendrik Bode). Design to insure stability often involves frequency compensation, one method of compensation being pole splitting.
The high-pitched squeal that sometimes occurs in audio systems, PA systems, and rock music is known as audio feedback. If a microphone is in front of a speaker that it is connected to, the noise put into the microphone will come out of the speaker. Since the microphone is in front of the speaker, the original sound (now coming from the speaker) goes back into the microphone. This happens over and over, getting louder each time. This process produces the squeal.
The processing and control of feedback is engineered into many electronic devices and may also be embedded in other technologies.
If the signal is inverted on its way round the control loop, the system is said to have negative feedback; otherwise, the feedback is said to be positive. Negative feedback is often deliberately introduced to increase the stability and accuracy of a system by correcting unwanted changes. This scheme can fail if the input changes faster than the system can respond to it. When this happens, the lag in arrival of the correcting signal results in unintended positive feedback, causing the output to oscillate or hunt[7] Oscillation is usually an unwanted consequence of system behaviour.
Harry Nyquist contributed the Nyquist plot for assessing the stability of feedback systems. An easier assessment, but less general, is based upon gain margin and phase margin using Bode plots (contributed by Hendrik Bode). Design to insure stability often involves frequency compensation, one method of compensation being pole splitting.
The high-pitched squeal that sometimes occurs in audio systems, PA systems, and rock music is known as audio feedback. If a microphone is in front of a speaker that it is connected to, the noise put into the microphone will come out of the speaker. Since the microphone is in front of the speaker, the original sound (now coming from the speaker) goes back into the microphone. This happens over and over, getting louder each time. This process produces the squeal.
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