18WuD2x

192 diode-capacitor memory cell • diode peak detector
conductor diode. A data pulse forward-biases the
diode and charges the capacitor, which remains
charged, thus holding the data bit, because of the
long time constant of the high capacitance and
the high back resistance of the diode.
diode characteristic The current-versus-voltage
curve for a diode.
diode checker An instrument for testing semiconductor
diodes. There are two forms: A static
checker, which measures forward and reverse
current; and a dynamic checker (see DYNAMIC
DIODE TESTER), which displays the entire diode
response curve on an oscilloscope screen.
diode chopper A chopper using an alternately biased
diode as the switching element.
diode clipper A clipper using one or more diodes.
A single biased diode will limit the positive or negative
peak of an applied alternating-current (ac)
voltage, depending on diode polarity and bias.
Two biased diodes with opposing polarity will clip
both peaks. Also see LIMITER.
Input
diode clipper
Output
diode converter See DIODE MIXER.
diode current The forward or reverse current flowing
through a diode.
diode current meter A direct-current (dc) milliammeter
or microammeter with a semiconductor-diode
rectifier that allows the measurement of
alternating current (ac).
diode curve changer A diode or network of diodes
used to make a linear current-voltage curve acquire
some nonlinear shape.
diode demodulator See DEMODULATOR PROBE
and DIODE DETECTOR.
diode detector A detector circuit in which a diode
demodulates a signal. The diode, a simple device,
provides linear response at high signal amplitudes,
but affords no amplification.
diode feedback rectifier 1. In a rectified-carrier,
negative-feedback system for an amplitudemodulated
(AM) transmitter, the diode that
rectifies the modulated carrier and provides the
audio envelope for use as negative-feedback
voltage. This voltage is applied to the speech
amplifier/modulator channel to reduce distortion,
noise, and hum, at the same time providing
automatic modulation control. 2. The diode that
rectifies a part of the signal at the output of an
audio amplifier and provides a proportional
direct-current (dc) voltage for use as bias in an
automatic-gain-control (AGC) circuit.
diode field-strength meter A simple meter for
measuring the intensity of a radio-frequency
(RF) electromagnetic field. It consists of a short
whip antenna, an inductance-capacitance (LC)
tuned circuit, a diode detector, and a directcurrent
(dc) microammeter. The deflection of the
meter is roughly proportional to the RF signal
voltage.
diode gate A passive switching circuit of biased
diodes. Also see AND CIRCUIT and OR CIRCUIT.
diode impedance The vector sum (resultant) of the
resistive and reactive components of a diode. In a
semiconductor diode, the inductive component of
reactance is almost entirely the inductance of
leads and electrodes, whereas the capacitive component
of reactance is the shunting capacitance
between leads and electrodes, plus the voltagevariable
capacitance of the pn junction. The
resistive component is almost entirely the voltage-variable
resistance of the pn junction.
diode isolation A means of insulating an integrated-circuit
chip from its substrate. The chip is
surrounded by a pn junction that is reversebiased.
This prevents conduction between the
chip and the substrate.
diode lamp See LASER DIODE.
diode laser See LASER DIODE.
diode light source See LASER DIODE.
diode limiter See DIODE CLIPPER.
diode load 1. The current drawn from a diode acting
as a rectifier or demodulator. 2. The output
(load) resistor into which a diode operates.
diode load resistance The required value for a
diode load resistor.
diode load resistor A resistor usually connected to
the output of a diode rectifier or diode detector.
diode logic Digital circuitry, such as AND and OR
circuits, using diodes as the principal components.
diode matrix In some digital devices, a grid of
wires, the intersections of some being interconnected
through diodes, whose polarities determine
circuit operation. A series of AND circuits is
provided by this arrangement, which acts as a
high-speed rotary switch when it is supplied with
input pulses.
diode mixer A frequency converter that operates
via the nonlinearity of semiconductor diodes.
diode noise limiter A noise limiter circuit having
one or more biased diodes.
diode oscillator An oscillator based on the negative
resistance or breakdown characteristics of
certain diodes, such as high-reverse-biased germanium
diodes, tunnel diodes, Gunn diodes, and
four-layer diodes. It is generally used at microwave
frequencies.
diode pack A device containing more than one
diode. An example is the full-wave bridge-rectifier
integrated circuit.
diode peak detector A diode detector whose load
resistance is high at modulation frequencies; the
voltage across the resistance is proportional to
the peak amplitude of the modulated signal.