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# Q factor

In physics and engineering the quality factor or Q factor is a dimensionless parameter that describes how underdamped an oscillator or resonator is, and characterizes a resonator's bandwidth relative to its centre frequency. [1]

74 relations: AC power, Acoustic resonance, Amplitude, Angular frequency, Asymptote, Atomic clock, Attenuation, Bandwidth (signal processing), Bessel filter, Brass instrument, Butterworth filter, Capacitance, Capacitor, Chu–Harrington limit, Complex conjugate, Complex number, Conservative force, Crystal oscillator, Damping ratio, Dimensionless quantity, Dissipation factor, Drag (physics), Electrical resistance and conductance, Engineering, Exponential decay, Factor of safety, Frequency, Friction, Full width at half maximum, Group delay and phase delay, Harmonic oscillator, Heaviside step function, Helmholtz resonance, Hertz, Impulse response, Inductance, Inductor, Kinetic energy, Laser, Linear time-invariant theory, Low-pass filter, Negative feedback, Octave, Octave (electronics), Optical cavity, Optics, Oscillation, Oscillator linewidth, Oscillator phase noise, Phase margin, ... Expand index (24 more) »

## AC power

Power in an electric circuit is the rate of flow of energy past a given point of the circuit.

## Acoustic resonance

Acoustic resonance is a phenomenon where acoustic systems amplify sound waves whose frequency matches one of its own natural frequencies of vibration (its resonance frequencies).

## Amplitude

The amplitude of a periodic variable is a measure of its change over a single period (such as time or spatial period).

## Angular frequency

In physics, angular frequency ω (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate.

## Asymptote

In analytic geometry, an asymptote of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the x or y coordinates tends to infinity.

## Atomic clock

An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.

## Attenuation

In physics, attenuation or, in some contexts, extinction is the gradual loss of flux intensity through a medium.

## Bandwidth (signal processing)

Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies.

## Bessel filter

In electronics and signal processing, a Bessel filter is a type of analog linear filter with a maximally flat group/phase delay (maximally linear phase response), which preserves the wave shape of filtered signals in the passband.

## Brass instrument

A brass instrument is a musical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips.

## Butterworth filter

The Butterworth filter is a type of signal processing filter designed to have a frequency response as flat as possible in the passband.

## Capacitance

Capacitance is the ratio of the change in an electric charge in a system to the corresponding change in its electric potential.

## Capacitor

A capacitor is a passive two-terminal electrical component that stores potential energy in an electric field.

## Chu–Harrington limit

In electrical engineering and telecommunications the Chu–Harrington limit or Chu limit sets a lower limit on the Q factor for a small radio antenna.

## Complex conjugate

In mathematics, the complex conjugate of a complex number is the number with an equal real part and an imaginary part equal in magnitude but opposite in sign.

## Complex number

A complex number is a number that can be expressed in the form, where and are real numbers, and is a solution of the equation.

## Conservative force

A conservative force is a force with the property that the total work done in moving a particle between two points is independent of the taken path.

## Crystal oscillator

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency.

## Damping ratio

Damping is an influence within or upon an oscillatory system that has the effect of reducing, restricting or preventing its oscillations.

## Dimensionless quantity

In dimensional analysis, a dimensionless quantity is a quantity to which no physical dimension is assigned.

## Dissipation factor

In physics, the dissipation factor (DF) is a measure of loss-rate of energy of a mode of oscillation (mechanical, electrical, or electromechanical) in a dissipative system.

## Drag (physics)

In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.

## Electrical resistance and conductance

The electrical resistance of an electrical conductor is a measure of the difficulty to pass an electric current through that conductor.

## Engineering

Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations.

## Exponential decay

A quantity is subject to exponential decay if it decreases at a rate proportional to its current value.

## Factor of safety

Factors of safety (FoS), is also known as (and used interchangeably with) safety factor (SF), is a term describing the load carrying capacity of a system beyond the expected or actual loads.

## Frequency

Frequency is the number of occurrences of a repeating event per unit of time.

## Friction

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

## Full width at half maximum

Full width at half maximum (FWHM) is an expression of the extent of function given by the difference between the two extreme values of the independent variable at which the dependent variable is equal to half of its maximum value.

## Group delay and phase delay

In signal processing, group delay is the time delay of the amplitude envelopes of the various sinusoidal components of a signal through a device under test, and is a function of frequency for each component.

## Harmonic oscillator

In classical mechanics, a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force, F, proportional to the displacement, x: where k is a positive constant.

## Heaviside step function

The Heaviside step function, or the unit step function, usually denoted by or (but sometimes, or), is a discontinuous function named after Oliver Heaviside (1850–1925), whose value is zero for negative argument and one for positive argument.

## Helmholtz resonance

Helmholtz resonance or wind throb is the phenomenon of air resonance in a cavity, such as when one blows across the top of an empty bottle.

## Hertz

The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second.

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## Impulse response

In signal processing, the impulse response, or impulse response function (IRF), of a dynamic system is its output when presented with a brief input signal, called an impulse.

## Inductance

In electromagnetism and electronics, inductance is the property of an electrical conductor by which a change in electric current through it induces an electromotive force (voltage) in the conductor.

## Inductor

An inductor, also called a coil, choke or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.

## Kinetic energy

In physics, the kinetic energy of an object is the energy that it possesses due to its motion.

## Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.

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## Linear time-invariant theory

Linear time-invariant theory, commonly known as LTI system theory, comes from applied mathematics and has direct applications in NMR spectroscopy, seismology, circuits, signal processing, control theory, and other technical areas.

## Low-pass filter

A low-pass filter (LPF) is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency.

## Negative feedback

Negative feedback (or balancing feedback) occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances.

## Octave

In music, an octave (octavus: eighth) or perfect octave is the interval between one musical pitch and another with half or double its frequency.

## Octave (electronics)

In electronics, an octave (symbol oct) is a doubling or halving of a frequency.

## Optical cavity

An optical cavity, resonating cavity or optical resonator is an arrangement of mirrors that forms a standing wave cavity resonator for light waves.

## Optics

Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it.

## Oscillation

Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states.

## Oscillator linewidth

The concept of a linewidth is borrowed from laser spectroscopy.

## Oscillator phase noise

0,..., t6) one can see that the deviation in amplitude dissipates while the deviation in phase does not.| --> Oscillators inherently produce high levels of phase noise. That noise increases at frequencies close to the oscillation frequency or its harmonics. With the noise being close to the oscillation frequency, it cannot be removed by filtering without also removing the oscillation signal. And since it is predominantly in the phase, it can be removed without any limiter. All well-designed nonlinear oscillators have stable limit cycles, meaning that if perturbed, the oscillator will naturally return to its limit cycle. This is depicted in the figure on the right (removed due to unknown copyright status). Here the stable limit cycle is shown in state space as a closed orbit (the ellipse). When perturbed, the oscillator responds by spiraling back into the limit cycle. However, by observing the time stamps, it is easy to see that while the oscillation returns to its stable limit cycle, it does not return at the same phase. This is because the oscillator is autonomous; it has no stable time reference. The phase is free to drift. As a result, any perturbation of the oscillator causes the phase to drift, which explains why the noise produced by an oscillator is predominantly in phase.

## Phase margin

In electronic amplifiers, the phase margin (PM) is the difference between the phase and 180°, for an amplifier's output signal (relative to its input) at zero dB gain.

## Photon

The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).

## Physics

Physics (from knowledge of nature, from φύσις phýsis "nature") is the natural science that studies matterAt the start of The Feynman Lectures on Physics, Richard Feynman offers the atomic hypothesis as the single most prolific scientific concept: "If, in some cataclysm, all scientific knowledge were to be destroyed one sentence what statement would contain the most information in the fewest words? I believe it is that all things are made up of atoms – little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another..." and its motion and behavior through space and time and that studies the related entities of energy and force."Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves."Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of the human intellect in its quest to understand our world and ourselves."Physics is an experimental science. Physicists observe the phenomena of nature and try to find patterns that relate these phenomena.""Physics is the study of your world and the world and universe around you." Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over the last two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the scientific revolution in the 17th century, these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy. Advances in physics often enable advances in new technologies. For example, advances in the understanding of electromagnetism and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.

## Potential energy

In physics, potential energy is the energy possessed by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors.

## Pulse (physics)

In physics, a pulse is a generic term describing a single disturbance that moves through a transmission medium.

## Pure tone

A pure tone is a tone with a sinusoidal waveform; this is, a sine wave of any frequency, phase, and amplitude.

## Q meter

A Q meter is a piece of equipment used in the testing of radio frequency circuits.

## Q multiplier

In electronics, a Q multiplier is a circuit added to a radio receiver to improve its selectivity and sensitivity.

## Q-switching

Q-switching, sometimes known as giant pulse formation or Q-spoiling, is a technique by which a laser can be made to produce a pulsed output beam.

## Qualitative property

Qualitative properties are properties that are observed and can generally not be measured with a numerical result.

## Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.

## Resonance

In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.

## Resonator

A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others.

## RLC circuit

An RLC circuit is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel.

## Sallen–Key topology

The Sallen–Key topology is an electronic filter topology used to implement second-order active filters that is particularly valued for its simplicity.

## Selectivity (electronic)

Selectivity is a measure of the performance of a radio receiver to respond only to the radio signal it is tuned to (such as a radio station) and reject other signals nearby in frequency, such as another broadcast on an adjacent channel.

## Sine wave

A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation.

## Sound box

A sound box or sounding box (sometimes written soundbox) is an open chamber in the body of a musical instrument which modifies the sound of the instrument, and helps transfer that sound to the surrounding air.

Superconducting radio frequency (SRF) science and technology involves the application of electrical superconductors to radio frequency devices.

## Transfer function

In engineering, a transfer function (also known as system function or network function) of an electronic or control system component is a mathematical function giving the corresponding output value for each possible value of the input to the device.

A tuned radio frequency receiver (or TRF receiver) is a type of radio receiver that is composed of one or more tuned radio frequency (RF) amplifier stages followed by a detector (demodulator) circuit to extract the audio signal and usually an audio frequency amplifier.

## Viscosity

The viscosity of a fluid is the measure of its resistance to gradual deformation by shear stress or tensile stress.

## Vuvuzela

The vuvuzela, also known as lepatata (its Tswana name), is a plastic horn, about long, which produces a loud monotone note, typically around flat 3 (the B below middle C).

## Western Electric

Western Electric Company (WE, WECo) was an American electrical engineering and manufacturing company that served as the primary supplier to AT&T from 1881 to 1996.

## Wind instrument

A wind instrument is a musical instrument that contains some type of resonator (usually a tube), in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece set at or near the end of the resonator.

## References

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