Page 40 - The Illustrated Dictionary of Electronics

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amp-hr • amplify 25

Direction of tical. 2. The number of decibels by which an AM-
PLIFIER circuit increases the amplitude of a sig-
flux flow nal. For voltage or current, this figure has
meaning only when the input and output
impedances are identical. See DECIBEL. 3. The
Wire
axis ALPHA or BETA of a bipolar transistor. 4. In
the operation of an electron tube, the ratio of
the derivative (instantaneous rate of change) of
the plate voltage to the derivative of the grid volt-
age, for zero change in plate current.
amplified ALC Abbreviation, AALC. An automatic-
level-control (ALC) system that uses the amplifi-
cation of the fed-back control signal. It is used in
RF power amplifiers, particularly single-sideband
Direction (SSB) linear amplifiers, to prevent overmodula-
of current tion and nonlinearity.
amplified back bias A declining voltage developed
across a fast-time-constant circuit in an amplifier
stage and fed back into a preceding stage.
Ampere’s Law
amplifier Any device that increases the magni-
tude of an applied signal. It receives an input
signal and delivers a larger output signal that, in
amp-hr One style of abbreviating AMPERE-HOUR. addition to its increased amplitude, is a replica
Also, Ah. of the input signal. Also see CURRENT AMPLI-
amplidyne A dynamo-like rotating dc machine FIER, POWER AMPLIFIER, and VOLTAGE AM-
that can act as a power amplifier because the re- PLIFIER.
sponse of the output voltage to changes in field amplifier diode Any semiconductor that can pro-
excitation is quite rapid. Used in servo systems. vide amplification in a suitable circuit or mi-
crowave system. See DIODE AMPLIFIER.
amplifier distortion A change in the waveform of a
signal, arising within an amplifier that is oper-
ated in compliance with specified conditions.
amplifier input 1. The terminals and section of an
amplifier that receive the signal to be amplified.
2. The signal to be amplified.
amplifier noise Collectively, all extraneous signals
present in the output of an amplifier when no
working signal is applied to the amplifier input
terminals.
amplifier nonlinearity A condition in which the
amplifier output signal does not exhibit a linear
relationship to the corresponding input signal.
Some amplifiers are designed to operate in a lin-
ear manner at all times, but many amplifier types
amplification 1. The process of increasing the need not function in this manner to be effective.
magnitude of a signal. This entails an input sig- Also see AMPLIFIER DISTORTION and LINEAR
nal controlling a local power supply to produce a AMPLIFIER.
larger output signal. Depending on the kind of in- amplifier output 1. The terminals and section of
put and output signals, amplification can be cat- an amplifier that deliver the amplified signal for
egorized as CURRENT, VOLTAGE, POWER, or external use. 2. The amplified signal.
some combination of these. 2. The qualitative sig- amplifier power The power level of the output sig-
nal increase resulting from the process in 1. 3. nal delivered by an amplifier (also called OUTPUT
The quantitative signal increase (resulting from POWER), or the extent to which the amplifier in-
the process in 1), expressed as a factor (such as creases the power of the input signal (also called
100) or in terms of decibels (dB). See AMPLIFICA- POWER AMPLIFICATION).
TION FACTOR and DECIBEL. amplifier response The performance of an ampli-
amplification factor 1. The ratio of the output fier throughout a specified frequency band. Fac-
voltage, current, or power to the input voltage, tors usually included are gain, distortion,
current, or power of an AMPLIFIER circuit. For amplitude versus frequency, and power output.
voltage or current, this ratio has meaning only amplify To perform the functions of amplification
when the input and output impedances are iden- (see AMPLIFICATION, 1).