Page 278 - Electrical Engineering Dictionary

feedback amplifier a circuit configura- the branch circuit panelboard(s) on a facil-
tion of amplifiers that has a feedback path. ity. For large systems, there may be more
A negative feedback configuration is com- than one level of feeder circuits. See also
monly used in amplifiers for its stable perfor- branch circuit.
mance, where a portion of the output signal
is added to the input signal at 180 degrees out feedforward amplifier a circuit config-
of phase. There are two types of basic feed- uration of low distortion amplifiers where a
back configurations: parallel feedback and a distorted voltage extracted from the output
series feedback.
signal is fed again to the output port so as to
cancel the distorted voltage included in the
feedback control the regulation of a re-
output signal.
sponse variable of a system in a desired man-
nerusingmeasurementsofthatvariableinthe
feedforward control a form of compen-
generation of the strategy of manipulation of
sation in which the measurement of a dis-
the controlling variable.
turbance is used to take preventative control
action before the effect of the disturbance is
feedback decoding a majority-logic de-
noted at the system output (and then only
coding method for decoding of convolutional
compensated by feedback control action). A
codes.
typical feedforward control configuration is
shown in the figure. The controller is de-
feedback linearization a method of us-
signed to have the same effect as the cascade
ing feedback to cancel out nonlinearities in
combination of the process and process D.
a dynamical system model so that the result-
ing closed-loop system model is linear. The
method uses tools from differential geome-
try. See also Lie derivative.
feedback oscillator electronic circuits de-
signed to provide specific signals of desired
waveshape. The feedback oscillator should
be envisioned as two basic network subsys-
tems: the active portion (amplifier) and the
passive (or feedback, FB) portion. The out-
A typical feedforward control configuration.
put of one subsystem is connected to the in-
put of the other and vice versa. The passive
network is lossy but provides the important
function of establishing the necessary elec- feedforward network See feedforward
trical phase shift to establish oscillation at neural network.
the desired frequency. See also Barkhausen
criterion. feedforward neural network one of two
primary classifications of neural networks
feeder overhead lines or cables that are (the other is recurrent). In a feedforward
used to distribute the load to the customers. neural network the x-vector input to the sin-
They interconnect the distribution substa- gle functional layer of processing elements
tions with the loads. (this input typically occurs via a layer of in-
put units) leads to the y-vector output in a
feeder circuit an electrical circuit de- single feedforward pass. An example of the
signed to deliver power from the service feedforward neural network is a multilayer
equipment or separately derived system to perceptron.

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2000 by CRC Press LLC