Electronic Engineering Dictionary

Fidelity. The faithful reproduction of a signal. The accuracy with which a system reproduces a signal at its output that faithfully maintains the essential characteristics of the input signal. The degree to which a system, or a portion of a system, accurately reproduces, at its output, the essential characteristics of the signal impressed upon its input or the result of a prescribed operation on the signal impressed upon its input.

Field. The electromagnet which furnishes the magnetic field that interacts with the armature in motors and generators.

Field-Effect Transistor. [FET] A transistor consisting of a source, a gate, and a drain. Current flow is controlled by the transverse electric field under the gate. A transistor in which the conduction is due entirely to the flow of majority carriers through a conduction channel controlled by an electric field arising from a voltage applied between the gate and source terminals. [FET Manufacturers]

JFET

Field Excitation. The creation of a steady magnetic field within the field windings by the application of a dc voltage either from the generator itself or from an external source.

Field of Force. A term used to describe the total force exerted by an action-at-a-distance phenomenon such as gravity upon matter, electric charges acting upon electric charges, and magnetic forces acting upon other magnets or magnetic materials.

Field-Programmable Gate Array. [FPGA] A type of user programmable gate array. See Programmable Logic Terms and Definitions for an enhanced definition. Also refer to Manufacturers of Programmable Logic Devices.

Field-Programmable Logic Array. [FPLA] A type of user programmable gate array. See Programmable Logic Terms and Definitions. Also refer to Manufacturers of Programmable Logic.

Field Strength. The magnitude of an electric, magnetic, or electromagnetic field at a given point.

FIFO. A buffer. A register or type of Memory. See First-In First-Out.

Filament. The cathode of a thermionic tube, usually a wire or ribbon, which is heated by current passing through it. Also refer to the listing on Vacuum Tube. A thin wire used to emit light in an Incandescent light bulb.

File Server. A high-capacity disk storage device or a computer that each computer on a network can use or access and retrieve files that can be shared among attached computers.

Film. Conductive or non-conductive material deposited on a glass or ceramic substrate. Used for passive circuit components, resistors, and capacitors.

Film Resistor. A resistor whose resistive element is a thin strip of conductive film deposited on a insulating core. Read more on Film Resistor

Filter. A selective network of resistors, capacitors, and inductors that offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies. In electronics, a device that transmits only part of the incident energy and may thereby change the spectral distribution of energy: (a) high-pass filters transmit energy above a certain frequency; (b) low-pass filters transmit energy below a certain frequency; (c) bandpass filters transmit energy of a certain bandwidth; (d) band-stop filters transmit energy outside a specific frequency band. Refer to the entry on Passive Filters.

Filter Capacitor. Any capacitor that is used to smooth out or filter voltage variations on a line. When used across the power nodes of an IC the filter capacitor is called a By-pass capacitor because the capacitor is said to by-pass the voltage variations [noise] to ground. Capacitors connected across the power leads in power supplies are called filter capacitors.

Filter Response. The output response of an active or passive filter. Refer to the definition of Filter for the different types. The graph shows the different orders of a Butterworth Filter, 1st order filter to fifth order.

Butterworth Filter

Final Power Amplifier. [FPA] The final stage of amplification in a transmitter.

Finished Wire. A wire which as had all the manufacturing operations completed and is ready for inspection.

Firmware. A software program which is permanently stored in Non-Volatile Memory [ROM]. Software that is embedded in a hardware device that allows reading and executing the software, but does not allow modification, e.g., writing or deleting data by an end user.

First Detector. See MIXER.

First-In First-Out. [FIFO] A queuing discipline in which entities in a queue leave the queue in the same order in which they arrive. A 74ALS236 TTL logic gate. An integrated circuit used to buffer or interface an incoming data stream arriving at one rate from one circuit to another circuit retrieving data at a different rate [using status flags to indicate when the FIFO becomes full or empty].

First-In Last-Out. [FILO] A queuing discipline in which entities in a queue leave the queue in the reverse order from that in which they arrived.

Fixed Attenuator. An attenuator with a set value that is not changeable. Also called a Pad.

Fixed Bias. A constant value of bias voltage.

Fixed Resistor. A resistor having a definite resistance value that cannot be adjusted. Also refer to Resistor Definitions, which resides in a different dictionary, or a listing of Resistor Manufacturers.

Fixed Spark Gap. A device used to discharge the pulse-forming network. A trigger pulse ionizes the air between two contacts to initiate the discharge.

Flag. In data transmission or processing, an indicator, such as a signal, symbol, character, or digit, used for identification. A flag may be a byte, word, mark, group mark, or letter that signals the occurrence of some condition or event, such as the end of a word, block, or message. Also see Protocol Definitions

Flag Sequence. In data transmission or processing, a sequence of bits used to delimit the beginning and end of a frame.

Flashover. A discharge between two points having different potential differences that is great enough to ionize the air and sustain an arc. The point at which a flash over will occur is determined by the distance between the two conductors, the shape of the conductors, the potential difference between the conductors and the air pressure. A lower air pressure will enhance a flash-over condition, while a vacuum decreases the possibility of flash-over, because there are no air molecules to ionize.

Flashover Voltage. The voltage at which flashover occurs between two conductors.

Flat Line. A transmission line that has no standing waves. This line requires no special timing devices to transfer maximum power.

Flat Pack. A type of surface mount IC package. Refer to the graphic in the right side-bar. Another example of a flat pack; Ceramic Quad Flat Pack IC graphical drawing.

Fleming Valve. A two-electrode vacuum tube used as a detector. Also refer to the listing on Vacuum Tubes.

Flexible Coaxial Line. A line made with an inner conductor that consists of flexible wire insulated from the outer conductor by a solid, continuous insulating material. Refer to the Definition of Coax Cable. Manufacturers of Coax Cable