Electronics Glossary – I
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| I | Symbol used to designate current. |
| I/O | Pertaining to the equipment used to communicate with a computer and the data involved. |
| I/O limited | Pertaining to a computer in which the speed of computer processing is limited by the speed of the input and/or output equipment. |
| IAD | integrated access devices |
| IC | Integrated Circuit |
| ICP | integrated communication provider |
| ID | Internal Diameter or Inside Diameter – The inside or internal diameter of a tubing. |
| IDC | Insulation Displacement Connector. A style of connector that slices through the cable insulation to make a connection.Eliminates the need to strip insulation. |
| identifier | A symbol whose purpose is to identify, indicate, or name a body of data. |
| IDP | Integrated detector/preamplifier. |
| IDSL | ISDN digital subscriber line |
| IEC | International Electrotechnical Commission. |
| IEEE | Institute of Electrical and Electronics Engineers. 802 Group develops Local Area Network standards and Metropolitan Area Network standards. |
| IEEE 488 | An interface for interconnecting programmable digital instruments. |
| IEEE 802.3 | Usually referred to as Ethernet. A networking protocol. |
| IEEE 802.5 | Usually referred to as token ring. A networking protocol. |
| IF | intermediate frequency |
| IF Bandwidth | The frequency interval in a receiver over which the amplifiers, filters and other components that process the IF are deigned to operate. |
| IF Impedance | The average of the time varying impedance of a mixer diode at some nominal IF frequency (usually 30 MHz). It is measured with an admittance bridge at a constant rectified current (normally 1 mA) produced by the LO signal. Most Schottky diodes will have IF impedances in the range of 150 – 400 ohms at 1 mA. |
| IGFET | Insulated-gate field-effect transistor. A general term lumping together all field-effect transistors having insulated gates regardless of fabrication process. |
| IH | The largest steady state current that, under specified ambient conditions, can be passed through a PolySwitch device without causing the device to trip. For SiBar devices, the current at which the device resets to a high-impedance state once the surge current dissipates. See also Hold Current. |
| IHOLD | The largest steady state current that, under specified ambient conditions, can be passed through a PolySwitch device without causing the device to trip. For SiBar devices, the current at which the device resets to a high-impedance state once the surge current dissipates. See also Hold Current. |
| IIL | I2L or Integrated-injection logic – A logic family in which gates consist essentially of only one transistor. Offers speeds comparable to TTL and packaging density and power consumption comparable to MOS. |
| ILEC | incumbent local exchange carriers (formerly RBOC) |
| Image Frequency | The frequency of an unwanted signal that may be incident on a down converter mixer that can produce the same IF as the desired signal. For example, if the desired frequency is 2 GHz and the LO frequency is 1.9 GHz, the image frequency is 1.8 GHz since the differences between 2.0 GHz and 1.9 GHz and between 1.9 GHz and 1.8 GHz are both 100 MHz. |
| Image Rejection Mixer | A mixer that is designed to reject signal at the image frequency. |
| Imax | The highest fault current that can safely be used to trip a PolySwitch device under specified conditions. Typically the lower the voltage dropped across the PolySwitch device in its tripped state, the higher the maximum interrupt current. Maximum interrupt currents are usually shown in this Databook at the maximum voltage. It may be possible to use a PolySwitch device at a higher interrupt current, but each such use must be individually qualified. |
| IMPATT | Acronym for “Impact Avalanche Transition Time”, which describes a class of semiconductor devices that can produce negative resistance. An IMPATT diode typically consists of 4 layers: N -p-i-p or p -n-i-n . In either case, when the p-n junction is under avalanche, there is a 90° phase shift between the resultant AC voltage across and current through the junction. The thickness of the I layer is designed to provide an additional 90° phase shift, thereby totaling 180°. |
| Impedance | The total opposition offered by a component or circuit to the flow of alternating or varying current at a particular frequency, including both the AC and DC component.. Impedance is expressed in ohms and is similar to the actual resistance in a direct current circuit. In computations, impedance is handled as a complex ratio of voltage to current. The ohm is the unit of impedance. Impedance is typically abbreviated as “z” or “Z”. The frequency-invariant, real component of impedance is resistance. The frequency-variant, imaginary component of impedance is reactance. The reciprocal of impedance is admittance. |
| impedance match | The condition in which the impedance of a component or circuit is equal to the internal impedance of the source, or the surge impedance of a transmission line, thereby giving maximum transfer of energy from source to load, minimum reflection, and minimum distortion. |
| Impedance Matching | The act of designing a circuit such that if the circuit is opened at any point, the impedance measured in either of the two resulting branches is equal. Maximum power is transferred through a circuit when impedances are matched. |
| Imperial Wire Gauge | A modification of the Birmingham Wire Gauge and the legal standard of Great Britain for all wires. It is variously known as Standard Wire Gauge (SWG), New British Standard (NBS), English Legal Standard, and Imperial Wire Gauge. |
| impregnate | To fill the voids and interstices of a material with a compound. This does not imply complete fill or complete coating of the surfaces by a hole-free film. |
| Impulse Test | A high-voltage test designed to locate pinholes in the insulation of a wire or cable by applying a voltage while the wire or cable is being drawn through an electrode. |
| In Phase | When two or more periodic, time-varying waveforms are simultaneously at the same phase angle and trending in the same direction. |
| Incident Wave | The wave front that impinges upon a device |
| Incremental Current | The DC bias current flowing through the inductor which causes an inductance drop of 5% from the initial zero DC bias inductance value. This current level indiciates where the inductance can be expected to drop significantly if the DC bias current is increased further. This applies mostly to ferrite cores in lieu of powdered iron. Powdered iron cores exhibit “soft” saturation characteristics. this means their inductance drop from higher DC levels is much more gradual than ferrite cores. The rate at which the inductance will drop is also a function of the core shape, i.e. air gap (Also see Saturation Current). |
| Incremental Permeability (µinc) | The permeability of a magnetic material about a specified operating point and applied magnetic field strength, especially under DC bias conditions. The incremental permeability is expressed as the slope of the B-H characteristic about the given operating point (dB/dH). |
| Index of refraction | The ratio of the velocity of light in free space to the velocity of light in a given material. Symbolized by n. |
| Index-matching material | A material, used at optical interconnection, having a refractive index close to that of the fiber core and used to reduce Fresnel reflections. |
| Individual Port Protection | Protection method where each output is protected by one circuit protection device (or output). For devices with multiple outputs per device, isolation is provided so that a port can respond to a fault condition without impacting the performance of the other port(s). |
| Inductance | That property of a circuit element which tends to oppose any change in the current flowing through it. The inductance for a given inductor is influenced by the core material, core shape and size, the turns count of the coil, and the shape of the coil. Inductors most often have their inductance values expressed in microHenries (µH) or milliHenries (mH). The schematic representation of inductance is designated as “L.” |
| Inductance Factor (AL) | The inductance rating of a core in nanoHenries per turn squared (nH/N2) based on a peak flux density of 10 gauss (1 milliTesla) at a frequency of 10 kHz. An AL value of 40 would produce 400µH of inductance for 100 turns and 40mH for 1000 turns. |
| induction generator | An induction generator is an induction machine, driven above synchronous speed by an external source of mechanical power. |
| induction motor | An induction machine which converts electric power, delivered to the primary circuit, into mechanical power. |
| inductive coupling | The coupling of energy from one circuit to another that results from the magnetic field generated by the source conductor. |
| Inductive Reactance | The opposition to alternating current flow presented by a capacitance. The symbol for capacitive reactance is XC. The unit is the ohm. The formula for capacitive reactance is XL = 2ðfL, where f is the frequency of the alternating current signal, and L is the inductance. |
| Inductor | A passive component designed to resist changes in current. Inductors arc often referred to as AC Resistors. The ability to resist changes in current and the ability to store energy in its magnetic field account for the bulk of the useful properties of inductors. Current passing through an inductor will produce a magnetic field. A changing magnetic field induces a voltage which opposes the field-producing current. This property of impeding changes in current is known as inductance. The voltage induced across an inductor by a change of current is defined as: V |
| information channel | The transmission and intervening equipment involved in the transfer of information in a given direction between two terminals. An information channel includes the modulator and demodulator, and any error-control equipment irrespective of its location, as well as the backward channel when provided. |
| inhibiting input | A gate input that blocks an output which might otherwise occur in a computer. |
| inhibitor, corrosion | A material which prevents or delays oxidation and galvanic action. |
| Initial Permeability (NO) | Permeability=u=B/H Initial permeability is that value of permeability when Bac=10gs. |
| Initial Resistance | The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given. |
| initialize | A program or hardware circuit which will return a program, a system, or a hardware device to an original state. |
| Input | The part of a circuit or device into which a signal is directed or applied. The signal that is applied to a circuit or device. |
| input bias current | The dc current that must be present at the amplifier input in order for the amplifier to be functional. It is measured with no signal applied. |
| Input Current | Current drawn from the input power bus by a converter when operating under nominal conditions |
| input impedance | The impedance that exists between the input terminals of an amplifier or transmission line when the source is disconnected. The circuit, signal level, and frequency must be specified. |
| Input Line Filter | A power filter placed on the input to a circuit or assembly that attenuates noise introduced from the power bus. The filter is designed to reject lise within a frequency band. Typically these filters arc low-pass filters meaning they pass low frequency signals such as the DC power and attenuate higher frequency signal which consist of mainly noise. Band pass or low pass filters are commonly made up of inductor and capacitor combinations. (Also see Noise, Attenuation, EMI and Pi-Filter). |
| input offset current | The difference in the currents into the two input terminals of an operational amplifier when the output is at zero. |
| input offset voltage | The voltage that must be applied between the two input terminals of an operational amplifier to obtain zero output voltage. |
| Input Reflected Ripple Current | AC component (typically generated by the switching circuit) measured at the input of a converter. Given as a peak-to-peak or RMS value. |
| Input Surge Current | Maximum, instantaneous input current drawn by a converter at turn on. Also called Inrush Current. |
| Input Transient | Spike or step change in the input to a converter. Input transient protection circuits arc used to shield sensitive components (such as the semiconductor switch) from possible damage due to transients. |
| Input Voltage Range | Minimum and maximum input voltage limits within which a converter operates to specifications. Often given as a ratio of high line to low line (i.e. a range of 9VDC to 18VDC is 2:1) |
| Inrush Current | Maximum, instantaneous input current drawn by a converter at turn on. Also called Input Surge Current. |
| Inrush Current Limiting | Protection circuit that limits the current a converter draws at turn on. |
| insert | In ARINC, “D” series, “W” series, and AMPLIMITE connectors, the insert is that part which holds the contacts in their proper arrangement and electrically insulates them from each other. It will accept contacts, or it may be preloaded with contacts or posts. It is NOT functional by itself, and must be inserted into a shell. |
| Insert Arrangement | The number, spacing, and arrangement of contacts in a termination assembly. |
| Insert Cavity | A defined hole in the connector insert into which the contacts are inserted. |
| insert molding | Two-step process wherein material is injection molded to form a part, which is then moved to a new mold as an insert, with another component molded against the first. |
| insertion force | The effort, usually measured in ounces, required to engage mating components. |
| insertion loss | The loss in load power due to the insertion of a component, connector, or device at some point in a transmission system. Generally expressed as the ratio – in decibels – of the power received at the load before insertion of the apparatus, to the power received at the load after insertion. |
| insertion tool | A tool used to insert contacts into a housing, insert, or module, or to insert connectors into panels or pc boards. |
| Inspection Hole | A hole placed at one end of a contact barrel to permit visual inspection, to ensure that the conductor has been inserted to the proper depth in the barrel prior to crimping or soldering. |
| Institute of Electrical and Electronic Engineers | IEEE – Professional organization that defines network standards. IEEE LAN standards are the predominant LAN standards today, including protocols similar or virtually equivalent to Ethernet and Token Ring. |
| instruction | A set of bits which will cause a computer to perform certain prescribed operations. A computer instruction consists of: 1)An operation code which specifies the operation(s) to be performed. 2) One or more operands (or addresses of operands in memory). 3) One or more modifiers (or addresses of modifiers) used to modify the operand or its address. Instruction can also be called an order. The signal that initiates the operation is called a command. |
| Insulated Gate Bipolar Transistor | IGBT – Power semiconductor device available for use in power conversion circuits. |
| Insulated Terminal | A solderless terminal with an insulated sleeve over the barrel to prevent a short circuit in certain installations. |
| Insulating Layer | A coating or volume of dielectric material. |
| insulation | A material having high electric resistance making it suitable for covering components, terminals, and wires, to prevent the possible future contact of adjacent conductors resulting in a short circuit. |
| insulation barrel | The portion(s) of a terminal, splice, or contact that is crimped. When designed to receive the conductor, it is called the wire barrel. When designed to support or grip the insulation, it is called the insulation barrel. Wire and/or insulation barrels may be either “open” or “closed” in design. Closed barrels resemble a hollow cylinder into which the wire must be inserted. Open barrels are formed into an open “U” and are common to most strip terminals manufactured by AMP Incorporated. |
| insulation crimp | The area of a terminal, splice, or contact that has been formed around the insulation of the wire. |
| insulation displacement | A terminating technique whereby an insulated wire is forced into a restrictive slot in a terminal, during which time the wire insulation is displaced, and the bare wire engages the sides of the slot. |
| insulation grip | Certain crimp contacts have extended cylinders at the rear designed to accept the bared wire and a small length of its insulation. When crimped, both the wire and insulation are held firmly in place. This prevents the wire from being exposed due to insulation receding from the terminal. |
| insulation piercing | A method of crimping whereby lances cut through the insulation of the wire and enter into the strands and make electrical contact thus eliminating stripping of the wire. |
| Insulation Resistance | Minimum electrical resistance permitted between any pair of contacts and between conductors and grounding devices of the same connectors in various combinations. An indication of the insulating properties of a material. |
| insulation support | An extended barrel or additional barrel at the rear of a terminal or contact which is crimped around the wire insulation to give additional support against wire flexing and reduce the possibility of wire breakage immediately behind the wire barrel. This crimp is not considered “grip” and offers little protection against longitudinal tension when exerted on the wire insulation. |
| Insulation, Electrical | A nonconductive material usually surrounding or separating two conductive materials. Often called the dielectric in cables designed for highfrequency use. |
| Insulation, Thermal | A nonconductive material that prevents the passage of heat. |
| integrated circuit | An interconnected array of active and passive elements integrated with a single semiconductor substrate or deposited on the substrate by a continuous series of compatible processes, and capable of performing at least one complete electronic circuit function. Normally, only the input, output, and supply terminations are accessible. Also called monolithic circuit and monolithic integrated circuit. When transistors or other discrete components are separately mounted and connected, it is a hybrid integrated circuit. |
| integrated circuitry | A fabricated part which serves all or a portion of a function and which is constructed by etching, diffusing, doping, etc of a single piece of material. Sections of this material may be joined by the use of jumper wires or printed circuitry. |
| Integrated detector/preamplifier | A detector package containing a pin photodiode and transimpedance amplifier. |
| interaction | The effects of two or more elements, parts, assemblies, or equipments on each other – where each is performing a function. |
| Intercept Point | The point at which two lines intersect. |
| interchangeable | A connector of one manufacturer can be replaced with a connector of another manufacturer, and will provide the same function in the same panel space as the connector it is replacing. |
| Interconnection | The joining of one individual device with another. |
| Interface | (1) The point at which two systems or pieces of equipment are connected. (2) A connection between two systems or devices. A shared boundary defined by common physical interconnection characteristics, signal characteristics, and meanings of interchanged signals. |
| interfacial compression | The compression of the resilient material (face of mating inserts) that provides positive sealing and insulation when plug and receptacle are locked together. |
| interfacial connection | A conductor which connects conductive patterns on opposite sides of a printed circuit board or other base. May be accomplished with a platedthru hole. Also a feed-thru connection. |
| interfacial gap | Any gap between the interface of mated connectors. |
| interfacial junction | The junction that is formed by the interface of two mating connectors. This junction can be tightly compressed or loose, depending upon the requirements of the application. |
| interfacial 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. |
| interference protection | Those measures which shield or immunize sensitive areas of an equipment from electrical interference. |
| interlaced memory | A memory with sequentially addressed locations occupying physically separated positions in the storage media. |
| intermateable | When a connector manufactured by one company will mate directly with a connector manufactured by a different company. For example when an AMP 50-position “M” series block loaded with AMP Type III( ) pin contacts is mated with a 50-position Winchester “MRA” series block loaded with Winchester sockets. |
| Intermediate Frequency | The desired output frequency from the down conversion mixing process, which is normally the difference between the LO and signal frequencies, i.e., (LO-RF) or (RF-LO). |
| Intermodulation Distortion | The distortion produced by nonlinear impedance in a component or system when two or more signals with distinct frequencies are present. Intermodulation products occur at the sums and differences of all harmonics of the original signals. |
| Intermodulation Frequencies | Frequencies of signals that are generated as a result of the combination of harmonic generation and mixing action of multiple input signals by nonlinear impedances in a system or device. For the case where there are two input signals, the intermodulation frequencies that are produced are given by |
| Internal Diameter | ID – The inside or internal diameter of a tubing. |
| Internal Power Dissipation | Power dissipated (as heat) within the converter during normal operation. Primarily a function of the power handling capability and efficiency of the converter. Internal power dissipation is normally given as a maximum specification that cannot be exceeded without risking damage to the converter. |
| International Electrotechnical Commission | (IEC) Organization based in Switzerland that sets standards for electronic products and components. IEC does not conduct any testing; however, their standards have been adopted by many of the national safety/standards agencies. |
| Interstice | In a cable construction, the space or void left between or around the cabled components. |
| Intranet | A private network that uses Internet software and standards. |
| inverter | (1) In logic, a digital circuit which inverts the input signal, as for example, changing a 1 to a 0. This is equivalent logically to the NOT function. An inverter may also serve as a buffer amplifier. (2) Power conversion circuit that converts DC to AC power. |
| Inverter Transformer | A transformer driven in such a manner that an applied DC power is converted to AC power (square waveform). Quite often the core is driven into saturation to accomplish this function. |
| Ion Implantation | The introduction of free ions into a material by accelerating them, under the influence of a large electromagnetic field, through space into a target material such as a semiconductor wafer. Ion implantation is used in the semiconductor industry to add dopants to wafers at low temperature, rather than to use high temperature diffusion or epitaxial deposition techniques. |
| ionomer | A thermoplastic with polyethylene as a major component and containing covalent and ionic bonds. |
| IP | Internet protocol |
| Iron-Core Coil/Transformer | Coil/transformer wound around an iron core to increase its inductance. At audio frequencies the iron core consists of laminations of silicon steel insulated from each other by varnish or shellac. At radio frequencies the core consists of powdered iron mixed in a binder which insulates the particles from each other. |
| IRQ | Interrupt Request Line, it is used to connect between CPU and peripheral |
| Irradiation | In insulations, the exposure of the material to high-energy emissions for the purpose of favorably altering the molecular structure via crosslinking. |
| IS-95 | A digital mobile telephony air interface standard that uses CDMA transmission. |
| Isc Max | The maximum short circuit a PolySwitch device is tested at the maximum operating voltage as specified. |
| ISDN | Integrated Services Digital Network- A CCITT networking standard devised to provide end-to-end, simultaneous handling of digitized voice and data traffic on the same link |
| ISO | International Standard Organization. |
| Isolated Output | See Floating Output |
| Isolation | Electrical separation between the input and output of a converter; Normally determined by transformer characteristics and component spacing. Referring to isolation is specified in values of resistance (RISO, typically megohms) and capacitance (CISO, typically pF). |
| Isolation Capacitance | Electrical separation between the input and output of a converter; Normally determined by transformer characteristics and component spacing. Referring to isolation is specified in values of resistance (RISO, typically megohms) and capacitance (CISO, typically pF). |
| isolation diffusion | The first diffusion of a monolithic integrated circuit. Its purpose is to generate the back-to-back junctions which isolate all active devices from one another. |
| Isolation Resistance | Electrical separation between the input and output of a converter; Normally determined by transformer characteristics and component spacing. Referring to isolation is specified in values of resistance (RISO, typically megohms) and capacitance (CISO, typically pF). |
| Isolation Transformer | Transformer with a one-to-one turns ratio. connected between the a.c. power input to a piece of equipment and the a.c. line, to minimize shock hazard. |
| Isolation Voltage | Maximum voltage (AC or DC) that can be continuously applied between isolated circuits without a breakdown occuring. On converters, this is normally specified as input-output or input-case isolation. Minimum isolation voltage levels be maintained to meet most safety regulations. Also see Breakdown Voltage, High Potential and Isolation. |
| Isolator | A three port circulator with one of its ports terminated with its characteristic impedance. |
| Isotropic | Having magnetic properties that are independent of the magnet orientation. Most magnetic materials are anisotropic as cast or powdered: each crystallite has a preferred direction of magnetic orientation. If the particles are not physically oriented during manufacture of the magnet, this results in random arrangement of the particles and magnetic domains, and produces isotropic magnetic properties. Conversely, orienting the material during the manufacture results in an anisotropic magnet. |
| ISP | Internet Service Provider |
| IT | The smallest steady state current that, if passed through a PolySwitch device, will cause the device to trip, under specified conditions. |
| ITAR | International Traffic in ARMS Regulations |
| ITS | Intelligent Transport Systems (eg fm Signav) |
| ITU | International Telecommunications Union |
| I-V Transfer Characteristics | The curve that is produced when the current that flows in a device is plotted against the voltage that is impressed across the device. The I-V transfer characteristic of a passive component, such as a resistor, capacitor or inductor is linear. The I-V transfer characteristic of a semiconductor junction is exponential. |
| IXC | Interexchange Carrier- (1)A long-distance telephone company offering circuit-switched, leased-line or packet-switched service or some combination. (2) Any individual, partnership, association, joint-stock company, trust, governmental entity or corporation engaged for hire in interstate or foreign communication by wire or radio, between two or more exchanges. |