Electronics Glossary – F

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Term Definition
F connector A common coaxial connector used for video applications (CATV).
F crimp A crimp that brings the center of the barrel along an open seam downward into a V.
face A connection between two systems or devices. A shared boundary defined by common physical interconnection characteristics, signal characteristics, and meanings of interchanged signals.
face seal Sealing of a multiple contact connector over the whole area of the interface to provide sealing around each contact. This is usually done by providing a soft insert material on one or both of the connectors which are in compression when mated. This provides an environmental seal between the interface of the plug and the interface of the receptacle and also increases the dielectric between contacts.
Failure The inability of a component or device to perform its intended function as specified by the manufacturer.
Failure Analysis A rigorous investigation of the fundamental causes of a failure.
Failure Criteria A specific description of a condition or characteristic of a device that precludes the device from performing its intended function as specified by the manufacturer
failure mechanism A structural or chemical defect which causes failure such as corrosion, poor bonds, or surface inversion.
Failure Mode The manner in which a failure occurs. Reason for which a converter either does not meet or stops meeting its specified parameters.
Failure Rate The mean proportion of failures per unit time, normally expressed in per cent per thousand hours of operation.
Fall time The time required for the trailing edge of a pulse to fall from 90% to 10% of its amplitude; the time required for a component to produce such a result. “Turn off time.” Sometimes measured between the 80% and 20% points.
Fan Cooled Use of a fan (or other air moving equipment) within a (sub) system to move air across heat producing components in order to reduce the ambient temperature. Also called forced convection.
fan in The number of logic inputs into a logic gate.
fan out The number of logic inputs that can be driven by the output of a logic gate.
Farad The unit of capacitance, abbreviated as “F”, equal to 1 coulomb per volt.
Faraday Shield Electrostatic shield that reduces coupling capacitance in transformers. The shield, which effectively reduces output common mode noise, is placed between the primary and secondary windings of a transformer.
fatigue The tendency of a metal to fracture in a brittle manner under conditions of repeated cyclic stressing at stress levels below its tensile strength.
Fault Mode Current Input current drawn by a converter when the output is shorted.
FCC Federal Communications Commission – US government agency that sets standards for, and governs the testing oc conducted and radiated emissions. These are system level standards, but they are typically used in specifying converters. Also see Electromagnetic Interference.
FDDI Fiber Distributed Digital Interface
FDM frequency division multiplexing
FDMA frequency division multiple access
Federal Communications Commission FCC – US government agency that sets standards for, and governs the testing oc conducted and radiated emissions. These are system level standards, but they are typically used in specifying converters. Also see Electromagnetic Interference.
Feed Forward Method of improving line regulation by directly sensing the input voltage of the converter. Also see Line Regulation.
Feedback A portion of the output signal of a device or system which is applied to the input of the system.
Feedback Loop The portion of a circuit whose purpose is to sample the output of a system or component, process the sample and apply the processed sample to the input of the system or component. Feedback loops are employed to either provide control or correction to a circuit, or in the case of an oscillator, to permit oscillation to occur.
Feedback Path The portion of a circuit whose purpose is to sample the output of a system or component, process the sample and apply the processed sample to the input of the system or component. Feedback loops are employed to either provide control or correction to a circuit, or in the case of an oscillator, to permit oscillation to occur.
feedthrough A connector or terminal block, usually having double-ended terminals which permit distribution and bussing of electrical circuits. Also used to describe a bushing in a wall or bulkhead, separating compartments at different pressure levels, with terminations on both sides.
feedthrough capacitor A feedthrough insulator that provides a desired value of capacitance between the feedthrough conductor and the metal panel or chassis through which the conductor is passing. Often used in bringing dc power into a shielded enclosure.
femto A prefix that stands indicates a factor of 10-15, abbreviated as “f”.
FEP Fluorinated ethylene propylene.
Ferrite Bead A small circular ferrite material structure. It is used to reduce radation
Ferrite Core Ferrite is a magnetic material that consists of a mixed oxide of iron and other elements that are made to have a crystalline molecular structure. Firing the ferrite material at a very high temperature for a specified amount of time and temperature profile creates the crystalline structure. The general composition of ferrite is xxFe2O4 where xx represents one or several metals. The most popular metal combinations are manganese and zinc (MnZn) and nickel and zinc (NiZn). These materials can be easily magnetized with little coercive force. Available in a variety of shapes and sizes, these ceramic magnetic cores are composed of ferric oxide and a combination of manganese, zinc, or nickel. The shapes EE, PQ, UU, ETD, and dual-slab are used for high frequency power applications. Telecommunications and low power applications use pot cores, touch tone cores, EP, and RM. Slugs, rods, and beads are used for radio frequency applications.
Ferromagnetism Ferromagnetic materials have atomic fields that align themselves parallel with externally applied fields creating a total magnetic field much greater than the applied field. Ferromagnetic materials have permeabilities much greater than air (1). Above the curie temperature, the ferromagnetic materials become paramagnetic.
Ferroresonat Transformer Transformer in which part of the core is driven in saturation by a resonant tank circuit. The output of the transformer, taken from the saturated protion, is relative immune to variations in input voltage.
ferrule A short tube used to make solderless connections to shielded or coaxial cable. Also molded into the plastic inserts of multiple contact connectors to provide strong, wear-resistant shoulders on which contact retaining springs can bear. The basis for alignment in many AMP fiber-optic connectors.
FET Field-effect transistor. A transistor controlled by voltage rather than current. The flow of working current through a semiconductor channel is switched and regulated by the effect of an electric field exerted by electric charge in a region close to the channel called the gate.
FET resistor In many MOSFET digital circuits, all components can be of a source-gate-drain structure. By adjusting the topology of the structure (and its location in the circuit) it may be considered primarily a resistor or capacitor or transistor. An FET resistor is an FET in which the gate is generally tied to the drain and used instead of a resistor load for an FET transistor.
FEXT Far End Crosstalk. Unwanted noise coupled onto a receive pair from a transmit pair at the far end of the system.
ffc Flexible flat cable; flat flexible cable; or flexible flat conductor. A form of multiple conductor cable consisting of parallel flat metal strips imbedded in a flat flexible insulating material.
Fiber Channel An industry-standard specification for computer channel communications over fiber optics and offering transmission speeds from 132 Mbaud to 1062 Mbaud and transmission distances from 1 to 10 km.
Fiber Distributed Data Interface network A token-passing ring network designed specifically for fiber optics and featuring dual counterrotating rings and 100 Mbps operation.
Fiber Optic Cable A transmission medium that uses glass or plastic fibers, rather than copper wire, to transport data or voice signals. The signals is imposed on the fiber via pulses (modulation) of light from a laser or a light-emitting diode (LED). Because of its high bandwidth and lack of susceptibility to interference, fiber-optic cable is used in long-haul or noisy applications.
Fiber Optics A method for the transmission of information (sound, pictures, data). Light is modulated and transmitted over high purity, hair-thin fibers of glass. The bandwidth capacity of fiber optic cable is much greater than that of conventional cable or copper wire.
Fiber-Optic Interrepeater Link A standard defining a fiber-optic link between two repeaters in an IEEE 802.3 network.
field (1) A region containing electric or magnetic lines of force, or both. (2) A category of information in a computer file.
Field Effect Transistor A three or more terminal transistor that consists of a channel and gate(s). At one end of the channel there is an electrode called the source, into which majority carriers flow from an external circuit. At the other end of the channel there is an electrode, called the drain, out of which electrons flow into the external circuit. Application of a voltage between the third terminal, known as the gate, and the source, establishes an electric field in the channel that changes the resistance between the source and drain, thereby changing the current that flows through the channel. In some FET’s, there is another gate terminal which is independent of the first gate terminal.
Field Strength (H) The parameter characterizing the amplitude of AC or DC field strength. The magnitude of current, number of turns, and winding geometry determine field strength.
file An organized collection of information consisting of records. The records in a file may or may not be sequenced according to a key contained in each record.
file maintenance The processing of a master file required to handle the nonperiodic changes in it. Examples: changes in number of dependents in a payroll file; the addition of new checking accounts in a bank.
filled cable A telephone cable construction in which the cable core is filled with a material that will prevent moisture from entering or passing through the cable.
Filler A material used in a cable construction to fill large interstices, thus providing a round construction; can be shaped, round, or in mastic forms. A nonfunctional member used in a cable to provide a more circular cross section.
film (1) An adherent layer of a foreign substance on a contact surface. (2) IC Circuits formed directly on the insulating substrate. May be further modified as either thick-film or thin-film integrated circuits.
film resistors A resistor in which the resistive material is a film over an insulating substrate. A resistor whose characteristics depend on film rather than bulk properties. The characteristics may be modified by either abrasive trim or laser trim techniques.
Filter A circuit or device whose purpose is to control electrical energy at a given frequency or over a range of frequencies. Groups of passive components are commonly used to construct many types of filters, including resistors, capacitors, and inductors.
Fine Leak Test A test performed on packaged semiconductors to determine the hermeticity of the package. Devices are immersed, under high pressure, in gaseous helium (He). They are placed in a vacuum chamber designed to detect the presence and amount of He. Packaged devices that have leak rates on the order of 10-8 cc/atm/sec or less are considered to be hermetic.
firmware Software in hardware form, as, for example, BASIC in ROM.
fishpaper A type of fiber paper used for insulating purposes where high mechanical strength is required.
Flag Power switch output that provides the USB controller the power switch device status. When FLG = High, the output MOSFET allows power to flow from the supply rail.
Flag delay time Design feature that delays the FLG notification signal in response to an abnormal condition (hot plug event, overcurrent surge, overtemperature condition). This feature minimizes unnecessary nuisance ‘trips’ caused by the inrush current of high capacitive loads.
flag terminal A type of terminal having the tongue or body project at 90° from the side of the terminal barrel, rather than being in line with – and extending from – the end of the barrel.
flame resistance The ability of material to extinguish flame once the source of heat is removed.
Flame Retardant A descriptor applied to a material that has been made or treated so as to resist burning.
flame retardants Either reactive compounds or additive compounds added to formulation to increase resistance to combustion. Reactive fire-retardant compounds become an integral part of the polymer structure, while additive fire-retardant chemicals are physically dispersed in the polymer.
Flame-resistant A descriptor applied to a material that is inherently resistant to burning.
flammability Measure of the material’s ability to support combustion.
flange A projection extending from – or around the periphery of – a connector, and having holes that provide for mounting the connector to a panel, or to a mating connector.
flash A thin film of material formed at the sides of a forging, casting or molded part where some of the material is forced between the faces of the forging dies or the mold halves. Also the excess metal extruded between both halves of crimping dies when making certain circumferential or symmetrical crimps. Also would include a thin deposit of plastic material usually at the base of molded-in pins.
Flat Braid A braided shield composed of flat strands.
Flat Cable A cable with each component in a single, flat plane.
Flat Conductor A conductor having a rectangular cross section, as opposed to a round or square cross section.
flat pack (1) A housing for delicate semiconductors or IC’s usually an alumina substrate although glass ceramic may be used. Thick film or thin film conductive paths on the ceramic connect the microcircuit active elements to the rest of the electronic system. (2) Any small, flat, square or rectangular integrated circuit packaged with leads coming from the sides of the package, in the same plane as the package.
Flatness The variation in attenuation or gain at a given bias level over the frequency band of interest.
Flex Life A measure of the susceptibility of a conductor or other device to failure due to fatigue from repeated bending.
flexibilizer An additive that makes a resin or rubber more flexible. More commonly called plasticizer.
flexible substrate Thick and thin film circuits have generally been deposited on rigid substrates, but it is possible to deposit these circuits on plastic substrates such as Kapton or Mylar which are flexible. Kapton and Mylar are trademarks.
flip-chip A method of attaching a silicon chip in which the bonding pads and circuit are placed face down to contact pads on the substrate.
flip-flop A basic digital building block that, at its simplest, uses two gates cross-coupled so that the output of one gate serves as the input of the other. It is capable of changing from one state to another on application of a control signal, but can remain in that state after the signal is removed. It thus serves as a basic storage element. Most flip-flops contain additional features to make them more versatile. Many digital circuits, such as registers and counters, are a number of flipflops connected together.
floating bushing A design feature which aids in the alignment of plug and receptacle shells during a rack and panel type of engagement. The floating bushing is generally an eyelet-type bushing which is fitted and retained in the plug mounting holes. Even though mounting screws are passed through the bushings and fastened to a frame, the plug is still permitted freedom of motion in all directions in seeking out the mating receptacle.
floating ground A grounding technique in which circuit grounds (return paths) are isolated from earth ground.
Floating Output Converter output that ungrounded and not referenced to another output. Typically, floating outputs are fully isolated and may be referenced positive or negative by the user. Outputs that are not floating share common return and as such, are referenced to one another.
Flow Soldering Flow Soldering is a tradename for specific wave soldering equipment manufactured by a company in England.
FLP field labor provider
fluorocarbons Resins which include fluorine in their molecular structure; the greater the fluorine content, the better are the polymer’s electrical, mechanical, thermal, and chemical properties.
fluoroplastics Polymers with monomers containing one or more atoms of fluorine or copolymers of such monomers.
Fluoropolymer A polymer that contains atoms of fluorine.
Flux (1) A liquid or solid that, when heated, exercises a cleaning and protective action upon surfaces. Used to promote or facilitate fusion during soldering or welding. (2) In magnetics, the magnetic field. Flux implies flow, which is not the case in magnetics. That is, no one has measured a magnetic ‘flow’. Flux is represented conceptually as ‘magnetic lines of force’. Flux density is measured in Gauss or Teslas. (3) Product of the average component of magnetic induction perpendicular to any given surface in a magnetic field by the area of that surface, expressed in webers.
Flux Density (B) The corresponding parameter for the induced magnetic field in an area perpendicular to the flux path. Flux density is determined by the field strength and permeability of the medium in which it is measured.
Flux Transfer Ratio The numeric amount of flux intercepted by the secondary winding and the total flux created by the applied ampere-turns.
Flyback Actually an isolated storage inductor, a flyback transformer is a combination of an isolating transformer, output inductor, and flywheel diode. These use a gapped core and have a power handling capability of 100VA. Storing energy in the gap when the switch is on and delivering energy to the load when the switch is off, they do not perform like standard transformers.
Flyback Converter Also called a “buck-boost” converter, this topology typically uses a single transistor switch and eliminates the need for an output inductor. Energy is stored in the transformer primary during the first half of the switching period when the transistor switch is on. During the second half or “flyback” period when the transistor is off, this energy is tranferred the transformer secondary and load. Also see Boost Regulator, Buck Regulator, Bridge Converter, Forward Converter, Push-Pull Converter and Resonant Converter.
Flyback Transformer Transformer used in a flyback power supply. Also called horizontal output transformer.
FM Frequency Modulation – A method of transmission in which the frequency of the carrier is varied in accordance to the signal.
FOIRL Fiber-optic interrepeater link.
Foldback Current Limiting Converter protection technique in which the circuit is protected under overload conditions by reducing the output current as the load approaches short circuit. This minimized internal power dissipation under short circuit conditions.
Forced Air Cooling Use of a fan (or other air moving equipment) within a (sub) system to move air across heat producing components in order to reduce the ambient temperature. Also called forced convection.
FORTRAN FORmula TRANslation. A computer-programming language designed mainly for scientific problems (expressed in algebraic notation).
Forward Bias Bias voltage applied to a semiconductor PN junction in the direction that causes electrons to flow from the n-type (cathode) to the p-type (anode) regions.
Forward Converter Also called a “Buck-Derived” converter, this topology, like the flyback converter, typically uses a single transistor switch. Unlike the flyback converter, energy is tranferred to the transformer secondary while the transistor switch is “on”, and stoed in a output inductor. See Boost Regulator, Buck Regulator, Bridge Converter, Flyback Converter, Push Pull Converter and Resonant Converter.
Forward Converter Transformer A transformer which operates by transferring power to the load during the on time and resetting in the off time. Since this transformer only transfers power during half of an input cycle it is required to be larger than a push-pull transformer for example.
FPGA Field Programmable Gate Array
FQPSK Filtered quadrature phase shift key modulation.
Fractional T1 A WAN communications service that provides the user with some portion of a T1 circuit which has been divided into 24 separate 64 kbps channels.
frame The surrounding portion (usually metal) of a multiple contact connector having a removable module or insert. The frame supports the insert, and provides a method for mounting the connector to a panel or a mating connector. See also shell.
Frame Relay A streamlined packet switching protocol designed to provide high-speed frame or packet switching with minimal delay and efficient bandwidth usage.
Free Convection Operating environment where the natural movement of air (unassisted by fans or blowers) maintains the power module within its operating limits. Also called natural convection.
free hanging A connector that is movable and not fixed to a board, panel, or frame. It will mate with another free-hanging connector or with a panelmount connector.
free standing A contact/terminal installed on a pc board and used without a housing.
Frequency The number of recurrences of a periodic phenomenon per unit time. In electronics, we refer to the frequency of electromagnetic radiation (radio waves) and alternating electrical current, which are periodic phenomena. The unit of frequency is the Hertz, abbreviated as “Hz.” Formerly, the unit of frequency was known as cycles per second, abbreviated as “cps.”
Frequency Band Frequency range over which the performance or characteristics of a circuit, device or component are described or specified.
Frequency Conversion The translation of a signal from one frequency to another.
Frequency Converter (or simply, Converter) A device or circuit that performs frequency conversion, such as a mixer.
Frequency Modulation the modification of the frequency of a higher frequency, constant magnitude carrier signal controlled by the amplitude and phase of a lower frequency baseband or audio signal.
Frequency Multiplication The increase in frequency of a signal by an integral factor.
Frequency of Operation See Switching Frequency
frequency response The measure of how the gain or loss of a circuit, device, or system varies with frequency. Also called frequency characteristic, amplitude- frequency response, response, response characteristic, and sine-wave response.
frequency, voice A frequency lying within that part of the audio range which is employed for speech transmission.. Note: Frequencies used for commercial transmission of speech usually lie within the range 200 to 3500 hertz (cps).
Fresnel reflection The reflection that occurs at the planar junction of two materials having different refractive indices; Fresnel reflection is not a function of the angle of incidence.
Fresnel reflection loss Loss of optical power due to Fresnel reflections.
fretting corrosion A form of accelerated oxidation that occurs at the interface of contacting materials undergoing slight, cyclic relative motion. All non-noble metals (tin) are susceptible to some degree and will suffer contact resistance increases.
Fringing Fields or Fringing Flux The field(s) associated with the divergence of the flux from the shortest path between poles in a magnetic circuit. Where flux passes through a high permeability into a lower permeability material, the flux redistributes and tends to have a ‘barreling effect’ between the two poles. See also leakage flux.
Front Release Contacts Connector contacts that are released from the front side of the connector and then removed from the back, wire side of the connector.
front-mounted A connector is said to be frontmounted when it is attached to the outside or mating side of a panel. A front-mounted connector can only be installed or removed from the outside of the equipment.
FSK Frequency-shift keying. Used for transmitting digital data. Logic 1 is assigned to one frequency, and logic 0 to another. The two frequencies are then transmitted serially, and decoded into binary bits at the other end.
Full Bridge Four power switches are used in a full bridge and usually utilize a single primary winding. Full supply voltage is obtained in both directions and utilizes the core and windings more effectively. Voltage on the switches does not exceed the supply voltage.
Full Bridge Converter Converter topology that typically operates as forward converter but uses a bridge circuit, consisting of four switching transistors, to drive the transformer primary. Also see Bridge Converter.
Full Load Maximum value of output load specified for a converter under continuous operating conditions.
Full Load Voltage Variations in winding resistance, turns ratio, and leakage can cause minor discrepancies in output voltage, which is the full load voltage.
Full Recovery Temperature, Minimum The minimum temperature required to fully shrink a product, that is, for the product to recover completely.
Full Winding A winding for toroidal cores that will result in 45% of the core’s inside diameter remaining.
Full-Wave Rectifier The process of converting alternating current into a unidirectional current, by removing or inverting that part of the wave laying on one side of the zero amplitude axis. There are two general types of retificitaion processes, half-wave and full-wave.
function Identifies the relationship within every combination of input conditions that will achieve one unique output. For example, in electronic circuits an “AND function” will be achieved only if all inputs are valid.
Fundamental Frequency The primary, lowest frequency component of a wave.
funnel entry Flared or widened entrance to a terminal or contact wire barrel. Permits easier insertion of the conductor, and helps assure that all wire strands will be directed into the wire barrel.
Fuse A type of overcurrent protection device that contains a metal wire which melts when too much current flows through it, thus breaking the circuit and protecting the circuit’s other components.
Fused coupler A method of making a multimode or single-mode coupler by wrapping fibers together, heating them, and pulling them to form a central unified mass so that light on any input fiber is coupled to all output fiber