18WuD2x

186 differential-input amplifier • differential-wound field
differential-input amplifier A differential amplifier
whose output is proportional to the difference
between two input signals—each applied between
an input terminal and common ground.
differential-input capacitance In a differential
amplifier, the capacitance between the input terminals.
differential-input impedance In a differential amplifier,
the impedance between the input terminals.
differential-input measurement For a differential
amplifier, a floating measurement made between
the input terminals.
differential-input rating In an operational amplifier,
the greatest difference signal that can be
placed between the inputs while allowing proper
operation.
differential-input resistance In a differential amplifier,
the resistance between the input terminals.
differential-input voltage In a differential amplifier,
the signal voltage presented to the floating
input terminals.
differential-input voltage range In a differential
amplifier, the range of signal voltages that can be
applied between the differential input terminals
without overdriving the amplifier.
differential input-voltage rating The maximum
differential-input voltage that can be applied
safely to a differential amplifier.
differential instrument A galvanometer or other
meter in which deflection results from the differential
effect of currents flowing in opposite directions
through two identical coils. Also see
DIFFERENTIAL GALVANOMETER.
differential keying A system of break-in keying, in
which the oscillator stage of a transmitter containing
a keyed amplifier is disabled when the key
is open to prevent interference with the receiver
at the keying station, and is enabled when the
key is closed.
differential-mode gain In an operational amplifier,
the ratio, in decibels, between the output
voltage and the differential input voltage.
differential-mode input In an operational amplifier
in differential mode, the difference between
the two input signal voltages.
differential-mode signal In a balanced threeterminal
circuit, such as the input of a differential
amplifier, a signal applied between the
floating (ungrounded) input terminals.
differential multiplexer An analog multiplexer
that selects both the high and low portion of the
input signal.
differential nonlinearity Incremental error from
an ideal analog output difference when the input
is changed by a certain value. Generally expressed
as a fraction of full-scale output.
differential permeability The derivative of normal
induction, with respect to magnetizing force.
differential phase In a television system tested
with a low-level, high-frequency sine-wave signal
(f 1 ) superimposed on a low-frequency, sine-wave
signal (f 2 ), the difference in phase shift of f 1
throughout the system for two specified levels of
f 2 .
differential phase-shift keying Keying of a carrier
by varying the carrier phase.
differential pressure The difference in pressure
between two points.
differential-pressure transducer A transducer
that delivers an output proportional to the difference
between two sensed actuating pressures.
differential protective relay A differential relay
that operates to protect equipment or personnel
when the difference between the two actuating
quantities reaches a prescribed level.
differential receiver A synchro differential that receives
the electrical output of two synchro transmitters.
The receiver can subtract one input
voltage from the other.
differential relay A relay actuated by the difference
between two currents or voltages.
differential selsyn A selsyn in which the position
assumed by the rotor is proportional to the sum
of rotor and stator field values.
differential stage See DIFFERENTIAL AMPLIFIER.
differential synchro See DIFFERENTIAL RE-
CEIVER and DIFFERENTIAL TRANSMITTER.
differential transducer A dual-input, single-output
sensor, such as a pressure transducer, that
is actuated by two sensed quantities and delivers
an output proportional to their difference.
differential transformer A variable inductance
transformer having a (usually cylindrical) core
that is moved in and out to provide adjustable
coupling between the interwound primary and
secondary windings. This permits adjustment of
the amplitude and phase of the transformer output
voltage, with respect to the input voltage.
differential transmitter A synchro differential
connected to a synchro transmitter. In a synchro
receiver supplied by this combination, the change
in rotor position is the algebraic difference between
the transmitter-rotor position and the differential-rotor
position.
differential unbalance For a differential amplifier,
the average difference in gain between the two
amplifier sections. Compare DIFFERENTIAL
GAIN.
differential voltage 1. The voltage difference between
the input signals to a differential device. 2.
The breakdown voltage minus the operating voltage
for a lamp.
differential voltage gain 1. The ratio, in decibels,
between the differential output and differential input
voltages of an amplifier. 2. The instantaneous
ratio, in decibels, between the rate of change of
the output signal voltage and the rate of change of
the input signal voltage in an amplifier.
differential-wound field In a motor or generator, a
field winding having series and shunt coils whose
fields are opposing.