D

DAC
Abbreviation for "digital to analog converter."

damping
Reduction in magnitude of oscillation due to energy being dissipated as heat.

darlington pair
An amplifier consisting of two bipolar junction transistors with their collectors connected together and the emitter of one connected to the base of the other. Circuit has an extremely high current gain and input impedance.

DC
Abbreviation for "direct current".

DC load line
A graph representing all possible combinations of voltage and current for a given load resistor in an amplifier.

DC offset
The change in input voltage required to produce a zero output voltage when no signal is applied to an amplifier.

DC power supply
Any source of DC power for electrical equipment.

dead short
Short circuit having zero resistance.

decade
A frequency factor of ten.

decibel
(dB) a logarithmic representation of gain or loss.

degenerative feedback
Also called negative feedback. A portion of the output of an amplifier is inverted and connected back to the input. This controls the gain of the amplifier and reduces distortion and noise.

delay time
The time for collector current to reach 10% of its maximum value in a BJT switching circuit.

depletion region
Thre area surrounding a pn junction that is depleted of carriers.

depletion mode
In a FET, an operating mode where reverse gate-source voltage is used to deplete the channel of free carriers. This reduces the size of the channel and increases its resistance.

depletion-mode MOSFET
A MOSFET designed to operate in either depletion mode or enhancement mode.

device
A component or part.

diac
A two terminal bidirectional thyristor. Has a symmetrical switching mode.

dielectric
Insulating material between two plates where an electrostatic field exists.

dialectric constant
Peoperty of a material that determines how much electrostatic energy can be stored per unit volume when unit voltage is applied.

dialectric strength
The maximum voltage an insulating material can withstand without breaking down.

differential amplifier
An amplifier in which the output is in proportion to the differences between voltages applied to its two inputs.

differentiator
A circuit in which the output voltage is in proportion to the rate of change of the input voltage. A high pass RC circuit.

diffusion
Tendency of conduction band electrons to wander across a pn junction to combine with valence band holes.

digital
Relating to devices or circuits that have outputs of only two discrete levels. Examples: 0 or 1, high or low, on or off, true or false etc.

diode
A two terminal device that conducts in only one direction.

DIP
Abbreviation for "dual in line package."

direct coupling
Where the output of an amplifier is connected directly to the input of another amplifier or to a load. Also known as DC coupling because DC signals are not blocked.

direct current
Current that flows in only one direction.

discharge
Release of energy stored in either a battery or a capacitor.

discrete component
Package containing only a single component as opposed to an integrated circuit containg many components in a single package.

dissipation
Release of electrical energy in the form of heat.

distortion
An undesired change in a waveform or signal.

distributed capacitance
Any capacitance other than that within a capacitor. For example, the capacitance between adjacent turns of wire in a coil.

distributed inductance
Any inductance other than that within an inductor. Example inductance in any conductor.

domain
A moveable magnetized area in a magnetized material. Also known as magnetic domain.

donor atoms
Pentavalent atoms that give up electrons to the conduction band in an N type semiconductor material.

doping
The process of adding impurity atoms to intrinsic (pure) silicon or germanium to improve the conductivity of the semiconductor material.

dot convention
Standard used with transformer symbols to indicate whether the secondary voltage is in phase or out of phase with the primary voltage.

drift
A problem that can develop in tuned amplifiers when the frequency of the tuned circuit changes due to temperature or component aging.

dropping resistor
Resistor whose value has been chosen to drop or develop a given voltage.

dry cell
DC voltage generating chemical cell using a non liquid (paste) electrolyte.

dual in-line package
Integrated circuit package having two rows of connecting pins.

dual trace oscilloscope
Oscilloscope that can simultaneously display two signals.

dynamic
Relating to conditions that are changing or in motion.
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