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Technical
Glossary - A
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| W,X,Y,Z | Spec.
Char., Number |
ABCD
Parameters
The set of parameters for a two-port device that
relates the input voltage and current to the output
voltage and current. The transfer function of
a cascaded circuit can be determined from the
product of the ABCD parameters for the individual
components from input to output.
Absolute
Temperature Scale
The temperature scale whose origin is the temperature
at which all molecular motion would cease. The
unit is the degree Kelvin (oK), which has the
same magnitude as a degree celsius (oC).
Absorptive
Device
A circuit or device that absorbs power, i.e.,
converts incident electrical energy into heat
or some other form of energy, rather than reflecting
electrical energy back to the source.
AC
Alternating current
Acceptor
A material that is intentionally added to a pure
semiconductor material to increase the population
of free holes in that semiconductor, resulting
in a net positive charge. A semiconductor that
has had acceptor material added to it is called
"p-type."
Active
Device
A component that changes the basic character of
an electric signal by amplification, rectification,
switching, etc. A device whose output is dependent
upon an external source of power other than the
input signal.
Active
Device
A component that has gain or operates in a non-linear
fashion to change the basic character of an electric
signal by, for example, amplification or rectification,
or a device comprised of such component, for example
a transistor switch. A device whose output is
dependent upon an external source of power other
than the input signal.
Active
Network
A circuit that produces gain.
Admittance
The ratio of current to voltage, the reciprocal
of impedance. The unit of admittance is the siemens
(S). Admittance is typically abbreviated as "y"
or "Y."
AGC
(See "automatic gain control").
Alternating
Current
The movement of charge carriers in a medium where
the direction in which the carriers move reverses
over time, typically with a fixed period, for
example 60 Hz 120 VAC household current.
AM
(See "amplitude modulation").
Amplifier
A circuit or device whose output signal is a faithful
version of the input signal but with increased
amplitude, usually specified as voltage or current.
Amplitude
Modulation
The modification of the magnitude of a higher,
constant frequency carrier signal controlled by
the amplitude and phase of a lower frequency baseband
or audio signal.
AMPS
Advanced Mobile Phone System. The original American
standard for analog wireless phone systems, used
primarily in North America, Latin America, Australia
and parts of Russia and Asia.
Angstrom
Unit of distance equal to 10-10 (10E-10) meter.
The symbol for the angstrom is Å.
Antenna
A structure that is intended to radiate electromagnetic
waves into or collect electromagnetic energy from
space.
Antistatic
Of or pertaining to the ability to either prevent
the accumulation of or to enable the dissipation
of static charge.
ATM
Asynchronous Transfer Mode. A communication protocol
for broadband transmission of voice, data and
video.
Attenuation
The degree to which an input signal is reduced
in amplitude at the output of a circuit or device.
Attenuation is typically expressed in dB.
Attenuator
A two port circuit or device that reduces the
amplitude of an input signal by a desired amount
typically expressed in decibels (dB). Attenuators
may be comprised of fixed resistors. PIN diodes
or FET's, or combinations of these.
Atto
A prefix that indicates a factor of 10-18, abbreviated
as "a."
Attoboy
An amount consisting of 10-10 boys.
Automatic
Gain Control
A feedback system that changes the gain of an
amplifier or the attenuation of an attenuator
in response to variations in magnitude of the
input signal, thereby maintaining the output signal
of the system at a constant magnitude.
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