Engineering Definitions
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

Q. Figure of merit of efficiency of a circuit or coil. Ratio of inductive reactance to resistance in servos. Relationship between stored energy (capacitance) and rate of dissipation in certain types of electric elements, structures, or materials.

Q-Band. A band of frequencies in the range of 36GHz to 46GHz. Note that letter designations are no longer used.

Q-Meter. A device used to measure the Quality factor [Q] of a circuit. The Q-meter is not in wide spread use.

Q-Point. See Quiescent State.

Quadrature. The state of being separated in phase by 90 degrees. Pertaining to the phase relationship between two periodic quantities varying with the same period, that is, with the same frequency or repetition rate, when the phase difference between them is one-quarter of their period.

Quadrature Amplitude Modulation. Quadrature modulation in which the two carriers are amplitude modulated. (QAM).

Quadrature Phase-Shift Keying. Phase-shift keying in which four different phase angles are used. In QPSK, the four angles are usually out of phase by 90 degrees. Synonyms quadriphase, quaternary phase-shift keying. quadrature phase-shift keying (QPSK).

Quality Factor. [Q]. In a reactive circuit, the ratio of the reactance in ohms divided by the resistance in ohms. The ratio of capacitive reactance to resistance. Q = XL/R = XC/R.

Quality (of Sound). The factor that distinguishes tones of pitch and loudness.

Quantization. A process in which the continuous range of values of an analog signal is sampled and divided into non-overlapping (but not necessarily equal) subranges, and a discrete, unique value is assigned to each subrange.

Quantization Level. In the quantization process, the discrete value assigned to a particular subrange of the analog signal being quantized.

Quantize. The process of restricting a variable to a number of discrete values.

Quantized Wave. A wave created by the arbitrary division of the entire range of amplitude (or frequency, or phase) values of an analog wave into a series of standard values. Each sample takes the standard value nearest its actual value when modulated.

Quantizing Distortion. Distortion that results from the quantization process.

Quantizing Noise. Distortion introduced by quantizing the signal.

Quantum-Mechanical Tunneling. The action of an electron crossing a PN junction because of tunnel effect.

Quartz. A mineral.

Quartz Clock: A clock containing a quartz oscillator that determines the accuracy and precision of the clock.

Quartz Crystal. Also called a crystal. [Oscillator Manufacturers]

Quartz Oscillator. An oscillator in which a quartz crystal is used to stabilize the frequency.

Quick Connect Terminal. A terminal or receptacle used for rapid inter-connection. Normally a flat metal blade is used as a quick connect terminal, the receptacle slides over metal blade using pressure to make the connection. Similar; Quick Disconnect.

Quick Disconnect. A type of connector shell or terminal that permits rapid locking and unlocking of two connector halves.

Quiescence. The state of an amplifier with no signal applied. The operating conditions that exist in a circuit when no input signal is applied to the circuit.

Quiescent Current. The current flowing in a circuit during a period in which a circuit element is not performing an active function in the system. The part of input current to a regulator which is not delivered to the load [less common definition].

Quiescent Power Consumption. The total power dissipated while a component is power by not operating [switching].

Quiescent State. The period when a transistor, tube, or other circuit element is not performing an active function in the circuit.

Quint. Five, as in five logic blocks or individual circuits within an integrated circuit package. Normally TTL style ICs have 4, 8, 16, or 32 individual components while ECL chips sometime have an odd number of circuits [however the fifth is almost always a bias circuit].

Qwerty Keyboard. A keyboard with the keys laid out in the same pattern as a typewriter.

PC motherboard

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