feedback circuit

Also found in: Dictionary, Thesaurus, Wikipedia.
Related to feedback circuit: negative feedback circuit

feedback circuit

[′fēd‚bak ‚sər·kət]
A circuit that returns a portion of the output signal of an electronic circuit or control system to the input of the circuit or system.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Feedback circuit

A circuit that returns a portion of the output signal of an electronic circuit or control system to the input of the circuit or system. When the signal returned (the feedback signal) is at the same phase as the input signal, the feedback is called positive or regenerative. When the feedback signal is of opposite phase to that of the input signal, the feedback is negative or degenerative.

The use of negative feedback in electronic circuits and automatic control systems produces changes in the characteristics of the system which improve the performance of the system. In electronic circuits, feedback is employed either to alter the shape of the frequency-response characteristics of an amplifier circuit and thereby produce more uniform amplification over a range of frequencies, or to produce conditions for oscillation in an oscillator circuit. It is also used because it stabilizes the gain of the system against changes in temperature, component replacement, and so on. Negative feedback also reduces nonlinear distortion. In automatic control systems, feedback is used to compare the actual output of a system with a desired output, the difference being used as the input signal to a controller. See Amplifier, Negative-resistance circuits, Servomechanism

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Theoretical values of the maximum suppression of phase noises in the spectrums of output signals of the proposed variants of the construction of signals formation channels based on hybrid frequency synthesizers with a DDS as a reference oscillator of the PLL are 13 dB, for a circuit with a DDS as a frequency divider the feedback circuits are 10 dB, and for the scheme with a DDS as a support oscillator of the PLL is characterized by a value of 6 dB [23].
In order to ensure full coverage and high-accuracy measurement of the geomagnetic field, a triaxial fluxgate magnetometer with linear dynamic range of [+ or -]65000 nT and resolution of 0.02 nT is designed, and its feedback circuit is shown in Figure 5.
FIGURE 2 illustrates a generalized feedback circuit connected to a source impedance.
If any of the feedback circuits are set incorrectly, then the amplifier will oscillate.
Parallel adders are combinatorial design which is not clocked, does not have any memory and feedback circuit elements for adding every bit position of the operands in the same time.
A three-phase BLDC system usually contains four fundamental blocks--a power stage to drive the motor, a feedback circuit to detect the rotor position and perform current sensing, an MCU or digital signal controller (DSC) to perform pulse-width modulation (PWM) control and housekeeping, and voltage regulators to power the digital, analog, and gate drive circuits.
The research team found that miR-124 and another key controller of the feedback circuit, HNF4a, showed reduced activity in the cancer cells.
Therefore, the total transfer function ([V.sub.o] / []) is the result of the ratio of the output operational amplifier [U.sub.2] and the load resistance R2 and photodiode feedback circuit with a resistor [R.sub.1].
For those who need a brush-up, Gonzalez thoughtfully describes the conditions for stable oscillation and analyzes the series feedback circuit in appendices.
An inductor with reactance [X.sub.L] and the internal nonlinear capacitance of the transistor compose the feedback circuit.
Hydraulic pressure is controlled by a closed-loop feedback circuit to a proportional valve in order to maintain uniform clamping force.