Add/Drop Multiplexer: A synchronous transmission network (SDH or Sonet) can carry multiple channels. An Add/Drop Multiplexer is a device that adds (inserts) or drops (removes) lower-data-rate channel traffic from the higher-rate aggregated channel. Also refered as Add-Drop Mux, A/D Mux, ADMs
ADS: Analog design system
Asymmetric Digital Subscriber Line (ADSL): A method for moving data over regular phone lines. An ADSL circuit carries much more data than a modem can encode on a regular phone connection. ADSL rides on the regular phone wires coming into the subscriber's premises (twisted pair copper).
Ambient Temperature: The average or mean temperature of the surrounding air which comes in contact with the equipment and instruments under test.
Ammeter: An instrument used to measure current.
Ampere (amp): A unit used to define the rate of flow of electricity (current) in a circuit; units are one coulomb (6.28 x 1018 electronics) per second. The symbol I is used for current in equations and A is the abbreviation for ampere. Amp. Also refered as I, amps, current, A Amplifier: An electrical circuit that produces an output that is a replica of the input. The output may be scaled or have increased drive, or it may provide isolation (so changes in output conditions do not affect the input or other outputs. It may perform other transformations (e.g. filtering or logarithmic drive).
Amplitude Span: The Y-axis range of a graphic display of data in either the time or frequency domain. Usually a log display (dB) but can also be linear.
Amplitude: A measurement of the distance from the highest to the lowest excursion of motion, as in the case of mechanical body in oscillation or the peak-to-peak swing of an electrical waveform.
Analog: A system in which an electrical value (usually voltage or current, but sometimes frequency, phase, etc.) represents something in the physical world. The electrical signal can then be processed, transmitted, amplified, and finally, transformed back into a physical quality.
For example: A microphone produces a current that is proportional to sound pressure. Various stages amplify, process, modulate, etc. Ultimately, a varying voltage is presented to a speaker which converts it back to sound waves.
By contrast, a digital system handles a signal as a stream of numbers.
Analog Switch: An analog switch (sometimes just called a "switch") is a switching device capable of switching or routing analog signals (meaning signals that can have any level within a specified legal range), based on the level of a digital control signal. Commonly implemented using a "transmission gate," an analog switch performs a function similar to that of a relay.
For example, an analog switch can turn an audio signal on or off based on a MUTE signal; or analog switches could send one of two signals to a headphone amplifier.
Analog Temperature Sensor: Temperature sensor with a continuous analog voltage or current output that is related, usually linearly, to the measured temperature.
Analog Output: A voltage or current signal that is a continuous function of the measured parameter.
Analog-to-Digital Converter (A/D or ADC): A device or circuit that converts analog signals into a stream of digital data. Also referred as A to D, ADC, Analog to Digital, A/D
ANSI: American National Standards Institute.
Anti-aliasing filter: An anti-aliasing filter is used before A/D conversion. It is a lowpass filter that removes signal components above the Nyquist frequency, thereby eliminating their sampled replicas (aliases) in the baseband.
Avalanche Photo Diode (APD): A photodiode designed to take advantage of avalanche multiplication of photocurrent to provide gain. As the reverse-bias voltage approaches the break-down voltage, hole-electron pairs created by absorbed photons acquire sufficient energy to create additional hole-electron pairs when they collide with ions. Thus a multiplication or signal gain is achieved.
ASIC: Application-specific integrated circuit.
ASCII: American Standard Code for Information Interchange. A seven or eight bit code used to represent alphanumeric characters. It is the standard code used for communications between data processing systems and associated equipment.
ASME: American Society of Mechanical Engineers.
ASTM: American Society for Testing and Materials.
ATE: Automatic test equipment; automated test equipment
AWG: American Wire Gage. A measure of wire thickness (which also dictates cross-sectional area, and for a given material, ampacity). Example: 24 AWG wire has a nominal diameter of 0.0201 inch or 0.511 mm. Also called the Brown and Sharpe Wire Gauge.
Arbitrary waveform generator
Bandwidth:
1. Bandwidth (BW) is a range of frequencies, or information, that a circuit can handle or the range of frequencies that a signal contains or occupies.BGA:
Ball grid array: A packaging technology.BIAS Current:
A very low-level DC current generated by the panel meter and superimposed on the signal. This current may introduce a measurable offset across a very high source impedance.Bidirectional:
The device accommodates signals traveling either direction though a single channelBit Error Rate:
A measure of the number of erroneous bits which can be expected in a specified number of bits in a serial stream.Bluetooth:
A technology that allows voice and data connections between a wide range of mobile and stationary devices through short-range digital two-way radio. For instance, it specifies how mobile phones, Wireless Information Devices (WIDs), computers and PDAs interconnect with each other, with computers, and with office or home phones.Bootstrap:
Often refers to using the output of a step-up converter to drive the main power FET switch, providing more gate drive than the input can supply alone. Also refers to using a switched capacitor to boost the voltage of a node.Broadband:
A transmission medium with enough bandwidth to carry multiple voice, video, or data channels simultaneously.
This technique is used, for example, to provide fifty CATV channels on one coaxial cable; or to provide Internet access over cable TV; or to add DSL to a voice-grade telephone line.
A common technique is frequency-division. Each channel is modulated to a different frequency band and combined in the transmission medium. It is demodulated to its original frequency at the receiving end. Channels are separated by guardbands (empty spaces) to ensure that each channel will not interfere with its neighboring channels.
Breakdown Voltage Rating: The dc or ac voltage which can be applied across insulation portions of a transducer without arcing or conduction above a specific current value.
Bridge Resistance: See Input impedance and Output impedance.
Buck: A "buck" or "step-down" switch-mode voltage regulator is one in which the output voltage is lower than its input voltage.
Buck Boost: A switch-mode voltage regulator in which output voltage can be above or below the input voltage.
Burn-In: A long term screening test (either vibration, temperature or combined test) that is effective in weeding out infant mortalities because it simulates actual or worst case operation of the device, accelerated through a time, power, and temperature relationship.
Burst Mode: 1) A temporary high-speed data-transfer mode that can transfer data at significantly higher rates than would normally be achieved with nonburst technology.
2) The maximum short-term throughput which a device is capable of transferring data.
CAT 3: Category 3: Refers to Ethernet cabling that satisfies the criteria for the EIA/TIA-568 standard's Category 3, which allows data transfers up to 10Mbps.
CAT 5: Category 5: Refers to Ethernet cabling that satisfies the criteria for the EIA/TIA-568 standard's Category 5, which allows data transfers up to 100Mbps.
CAD: Computer-aided design
CDMA: Code Division Multiple Access: A digital cellular technology that uses spread-spectrum techniques. Unlike GSM and other competing systems that use TDMA, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence.
Celsius (Centrigrade): A temperature scale defined by 0°C at the ice point and 100°C at boiling point of water at sea level.
Chatter: The rapid cycling on and off of a relay in a control process due to insufficient bandwidth in the controller.
Chip: 1. Integrated circuit: A semiconductor device that combines multiple transistors and other components and interconnects on a single piece of semiconductor material.
Clock: The device that generates periodic signals for synchronization.
Clock Jitter: A periodic waveform (especially a clock) is expected to cross certain thresholds at precisely timed moments. Variations from this ideal are called jitter.
CMR (Common-Mode Rejection): The ability of a panel meter to eliminate the effect of AC or DC noise between signal and ground. Normally expressed in dB at dc to 60 Hz. One type of CMR is specified between SIG LO and PWR GND. In differential meters, a second type of CMR is specified between SIG LO and ANA GND (METER GND).
Common Mode Rejection Ratio (CMRR): The ability of a differential amplifier to not pass (reject) the portion of the signal common to both the + and - inputs.
CODEC: Short for compressor/decompressor, a codec is any technology for compressing and decompressing data. Codecs can be implemented in software, hardware, or a combination of both.
Comparator: A comparator is a device that accepts two analog inputs, compares the inputs, and produces a binary output that is a function of which input is higher. If the non-inverting (+) input is greater than the inverting (-) input, then the output goes high. If the inverting (-) input is greater than the non-inverting (+) input, then the output goes low.
CMV (Common-Mode Voltage): The AC or DC voltage which is tolerable between signal and ground. One type of CMV is specified between SIG LO and PWR GND. In differential meters, a second type of CMV is specified between SIG HI or LO and ANA GND (METER GND).
Coherence Function.: A frequency domain function computed to show the degree of a linear, noise-free relationship between a system's input and output. The value of the coherence function ranges between zero and one, where a value of zero indicates there is no causal relationship between the input and the output. A value of one indicates the existence of linear noise-free frequency response between the input and the output.
Common Mode Rejection Ratio: The ability of an instrument to reject interference from a common voltage at its input terminals with relation to ground. Usually expressed in db (decibels).
Common Mode: The output form or type of control action used by a temperature controller to control temperature, i.e. on/off, time proportioning, PID.
Coulomb Sensitivity: Charge/unit acceleration, expressed in Pc/g (charge sensitivity).
Coulomb: A measurement of the quantity of electrical charge, usually expressed as pico coulomb (10-12 coulombs).
Crossover: In an output stage (or similar amplifying stage which uses one device to pull the signal up and another to pull the signal down), the region in which the high-side device is turning on and the low-side device is turning off, or vice versa.
Crowbar Circuit: A crowbar circuit is a power supply protection circuit that rapidly short-circuits ("crowbars") the supply line if the voltage and/or current exceeds defined limits. In practice, the resulting short blows a fuse or triggers other protection, effectively shutting down the supply.
CSA: Canadian Standards Administration.
Current: The rate of flow of electricity. The unit of the ampere (A) defined as 1 ampere = 1 coulomb per second.
Current Mode Controller: A DC-DC switching regulator which regulates its output voltage by varying the peak inductor current on a cycle-by-cycle basis to output a regulated voltage despite variations in load-current and input-voltage.
Current Sense Amplifier: An amplifier that measures current by measuring the voltage drop across a resistor placed in the current path. The current sense amp outputs either a voltage or a current that is proportional to the current through the measured path.
Cycle Time: The time usually expressed in seconds for a controller to complete one on/off cycle.
Data Converter: A/D or D/A converter: An electronic circuit that converts analog signals to digital, or vice-versa.
dB (Decibel): 20 times the log to the base 10 of the ratio of two voltages. Every 20 dBs correspond to a voltage ratio of 10, every 10 dBs to a voltage ratio of 3.162. For instance, a CMR of 120 dB provides voltage noise rejection of 1,000,000/1. An NMR of 70 dB provides voltage noise rejection of 3,162/1.
dB = 10 times the log of the ratio of the power of the two signals. This is equal to 20 times the ratio of their voltages, if the signals are driving equal impedances.
dBm: A unit that defines a signal level by comparing it to a reference level. The reference level of 0dBm is defined as 1mW. The signal level in dBm is 10 times the log of the signal's power over that of the 0dBm reference.
DC: Direct current; an electric current flowing in one direction only and substantially constant in value.
DC-DC: Any of the family of switch-mode voltage regulators, these devices use an inductor to store and transfer energy to the output in discrete packets, resulting in highly efficient power conversion.
Dense Wave Division Multiplexing (DWDM): The technology by which the frequencies of light carried on a single optical fiber are subdivided into discrete wavelengths, allowing for the greater transmission of data.
Design For Testability (DFT): Design For Testability (or Design for Test, or DFT) refers to design techniques that make products easier to test. Examples include the addition of test points, parametric measurement devices, self-test, diagnostics, test modes, and scan design.
Deviation: The difference between the value of the controlled variable and the value at which it is being controlled.
Dielectric Constant: Related to the force of attraction between two opposite charges separated by a distance in a uniform medium.
Differential Input: A signal-input circuit where SIG LO and SIG HI are electrically floating with respect to ANALOG GND (METER GND, which is normally tied to DIG GND). This allows the measurement of the voltage difference between two signals tied to the same ground and provides superior common-mode noise rejection.
Differential: For an on/off controller, it refers to the temperature difference between the temperature at which the controller turns heat off and the temperature at which the heat is turned back on. It is expressed in degrees.
Digit: A measure of the display span of a panel meter. By convention, a full digit can assume any value from 0 through 9, a 1/2-digit will display a 1 and overload at 2, a 3/4-digit will display digits up to 3 and overload at 4, etc. For example, a meter with a display span of ±3999 counts is said to be a 3-3/4 digit meter.
Digital potentiometer: A solid-state device that emulates a mechanical potentiometer, it is usually controlled via a simple interface.
Diode: A two-terminal device that rectifies signals (passes current in only one direction). Most commonly, a semiconductor consisting of a P-N junction, but diodes can also be realized using vacuum tube, point-contact, metal-semiconductor junction (Schottky), and other technologies.
Duty Cycle: The total time to one on/off cycle. Usually refers to the on/off cycle time of a temperature controller.
Digital Output: An output signal which represents the size of an input in the form of a series of discrete quantities.
Digital-to-Analog Converter (D/A or DAC): A data converter, or DAC, that receives digital data (a stream of numbers) and outputs a voltage or current proportional to the value of the digital data.
Drift: A change of a reading or a set point value over long periods due to several factors including change in ambient temperature, time, and line voltage.
Droop: A common occurrence in time-proportional controllers. It refers to the difference in temperature between the set point and where the system temperature actually stabilizes due to the time-proportioning action of the controller.
Dual-slope A/D Converter: An analog-to-digital converter which integrates the signal for a specific time, then counts time intervals for a reference voltage to bring the integrated signal back to zero. Such converters provide high resolution at low cost, excellent normal-mode noise rejection, and minimal dependence on circuit elements.
Duty Cycle: The total time to one on/off cycle. Usually refers to the on/off cycle time of a temperature controller.
Dynamic RAM (DRAM): Random-Access Memory that uses a continuous clock. Unlike SRAM, when DRAM is no longer clocked, its data is lost.
E: Volt
Electro-Absorption Modulators (EAM): Chip-level modulation devices often integrated into hybrid transponder devices, alongside lasers.
ECB: Electrically controlled birefringence
ECL: Emitter-coupled logic
ECM: Electret capacitor microphone
EEPROM: Electrically erasable programmable read-only memory
EFT: Electrical fast transient
EIA-JEDEC: Electronic Industries Association/Joint Electron Device Engineering Council
Electrical Interference: Electrical noise induced upon the signal wires that obscures the wanted information signal.
Electrode Potential (E): The difference in potential established between an electrode and a solution when the electrode is immersed in the solution.
Electronic Industries Association (EIA): A standards organization specializing in the electrical and functional characteristics of interface equipment.
Electromagnetic Compatibility (EMC): The ability of electronic equipment to be a "good electromagnetic neighbor": It neither causes, nor is susceptible to, electromagnetic interference
Electromagnetic Interference (EMI): Unwanted noise from electromagnetic radiation.
EPROM: Erasable programmable read-only memory
ESD: Electrostatic Discharge
ESD Protection: Devices added to input and output pins on an IC to protect the internal circuitry from the damaging effect of electrostatic discharge.
Equivalent Series Resistance (ESR): Effective Series Resistance is the resistive component of a capacitor's equivalent circuit.
F: Farad(s): Unit of capacitance
FB: Feedback
FCD: Fan count divisor
FCR: Fan conversion rate
FDD: Frequency-division duplex
FDM: A method for carrying multiple channels of information on one channel by dividing the available bandwidth among the channels.
Forward Error Correction (FEC): A technique for detecting and correcting errors from imperfect transmission by adding a small number of extra bits. FEC allows optical transmission over longer distances by correcting errors that can happen as the signal-to-noise ratio decreases with distance.
Firmware: Programs stored in PROMs.
Field-Effect Transistor (FET): A transistor in which the voltage on one terminal (the gate) creates a field that allows or disallows conduction between the other two terminals (the source and drain).
There are three varieties: The JFET (Junction Field-Effect Transistor); the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor); and the MESFET (Metal-Semiconductor Field-Effect Transistor).
The FET is one of two major kinds of transistor, the other being the Bipolar Junction Transistor.
Field Programmable Gate Array (FPGA): A family of general-purpose logic devices that can be configured by the end user to perform many, different, complex logic functions. It is often used for prototyping logic hardware.
Frequency Modulated Output: A transducer output which is obtained in the form of a deviation from a center frequency, where the deviation is proportional to the applied stimulus.
Frequency of Vibration: The number of cycles occurring in a given unit of time. RPM - revolutions per minute. CPM- cycles per minute.
Frequency Output: An output in the form of frequency which varies as a function of the applied input.
Frequency Synthesizer: A frequency synthesizer is an electronic circuit that uses an oscillator to generate a preprogrammed set of stable frequencies with minimal phase noise. Primary applications include wireless/RF devices such as radios, set top boxes, and GPS.
GaAs: Gallium arsenide: A semiconductor material used for optoelectronic products such as LEDs, and for high-speed electronic devices.
Gain: Gallium arsenide: A semiconductor material used for optoelectronic products such as LEDs, and for high-speed electronic devices.
Gate: 1. The controlling terminal of a FET. A voltage on the gate controls the current flow between the source and drain.
2. A basic logic element (e.g. AND, OR, NOT, NAND, NOR, XOR, etc.).
GBW: Gain bandwidth
GHz: Gigahertz
Gigabit: 1 billion bits-per-second.
GUI: Graphical user interface
H: Henry(ries): The unit of inductance.
Half Duplex: Data transmission over a circuit capable of transmitting in either direction, but not simultaneously.
Half Flash: An ADC architecture which uses a bank of comparators first to digitize the upper half bits, then uses a digital-to-analog converter (DAC) to subtract that voltage from the input, and then digitizes what remains of the input signal to get the lower half bits.
Harmonic Distortion: The presence of frequencies in the output of a device that are not present in the input signal, and are multiples of components of the input signal. Clipping is a common cause but other nonlinearities can also introduce harmonics.
HAST: Highly accelerated stress test; highly accelerated steam and temperature
Hertz (Hz): Units in which frequency is expressed. Synonymous with cycles per second.
HTML: Hyper Text Markup Language: Coding language used to create web pages.
HTTP: Hyper Text Transport/transfer Protocol
HVAC: Heating, Ventilation, and Air Conditioning.
Hz: Hertz: A measure of frequency.
I/O: Input/output
IC: Integrated circuit: A semiconductor device that combines multiple transistors and other components and interconnects on a single piece of semiconductor material.
ICA: Integrated circuit accumulator
IEC: IEC stands for the International Electrotechnical Commission.
IEEE: Institute of Electrical and Electronics Engineers
Impedance: Impedance, represented by the symbol Z, is a measure of the opposition to electrical flow. It is measured in ohms.
Input Impedance: The resistance measured across the excitation terminals of a transducer.
Input Impedance: The resistance of a panel meter as seen from the source. In the case of a voltmeter, this resistance has to be taken into account when the source impedance is high; in the case of an ammeter, when the source impedance is low.
Input Resistance (Impedance): The input resistance of a pH meter is the resistance between the glass electrode terminal and the reference electrode terminal. The potential of a pH-measuring electrode chain is always subject to a voltage division between the total electrode resistance and the input resistance.
Inrush Current: A momentary input current surge, measured during the initial turn-on of the power supply. This current reduces to a lower steady-state current once the input capacitors charge. Hotswap controllers or other forms of protection are often used to limit inrush current, because uncontrolled inrush can damage components, lower the available supply voltage to other circuits, and cause system errors.
Insulation Resistance: The resistance measured between two insulated points on a transducer when a specific dc voltage is applied at room temperature.
Infrared Data Association (Irda): A group of device manufacturers that developed a standard for transmitting data via infrared light waves.
IRO: Input-referred offset.
IRS: Interface register set.
IRSA: Interface register set address
IRSD: Interface register set data
ISO: International Standards Organization.
ISP: Internet Service Provider
ITU: International Telecommunication Union.
Joule (J): A measurement of energy or work. In mechanical systems, it's the a force of one Newton, moving an object a distance of one meter.
JALT: Jitter attentuator limit trip
JEDEC: Joint Electron Device Engineering Council.
JFET: A JFET, or junction field-effect transistor, or JUGFET, is a FET in which the gate is created by reverse-biased junction (as opposed to the MOSFET which creates a junction via a field generated by conductive gate, separated from the gate region by a thin insulator).
JIT: Just-in-time
Jitter: The slight movement of a transmission signal in time or phase that can introduce errors and loss of synchronization. More jitter will be encountered with longer cables, cables with higher attenuation, and signals at higher data rates. Also, called phase jitter, timing distortion, or intersymbol interference.
JPEG: Joint Photography Experts Group; more commonly, files that are compressed using the JPEG standard.
K: Kilo
Kb: Kilobit(s)
Kg: Kilogram(s)
KHz: Kilohertz
KW: Kilowatt(s)
Low Drop Out (LDO): A linear voltage regulator that will operate even when the input voltage barely exceeds the desired output voltage.
Load Impedance: The impedance presented to the output terminals of a transducer by the associated external circuitry. Leakage Inductance: Leakage inductance in a transformer is an inductive component that results from the imperfect magnetic linking of one winding to another.
In an ideal transformer, 100% of the energy is magnetically coupled from the primary to the secondary windings. Imperfect coupling causes some loss. The electrical equivalent is some self-inductance in series with the primary windings that are properly coupled. This series inductance is the "leakage inductance."
LED: Light-Emitting Diode: A semiconductor device that emits light (usually visible or infrared) when forward-biased.
Line Regulation: The ability of a power-supply voltage regulator to maintain its output voltage despite variations in its input voltage.
Linear: Having the property that the output is proportional to the input. E.g.:
VOUT = k*VIN
where k is a constant.
Linear Regulator: A voltage regulator that is placed between a supply and the load and provides a constant voltage by varying its effective resistance.
LL: Local loopback
Lm: Lumen(s)
Lm/W: Lumen(s) per watt
LNA: Low noise amplifier. Typical use: The first stage of a satellite receiver.
LO: Local oscillator
Load: The electrical demand of a process expressed as power (watts), current (amps) or resistance (ohms).
Loop Resistance: The total resistance of a thermocouple circuit caused by the resistance of the thermocouple wire. Usually used in reference to analog pyrometers which have typical loop resistance requirements of 10 ohms.
LS-TTL Compatible: For digital input circuits, a logic 1 is obtained for inputs of 2.0 to 5.5 V which can source 20 µA, and a logic 0 is obtained for inputs of 0 to 0.8 V which can sink 400 µA. For digital output signals, a logic 1 is represented by 2.4 to 5.5 V with a current source capability of at least 400 µA; and a logic 0 is represented by 0 to 0.6 V with a current sink capability of at least 16 MA. "LS" stands for low-power Schottky.
LS-TTL Unit Load: A load with LS-TTL voltage levels, which will draw 20 µA for a logic 1 and -400 µA for a logic 0.
LVC: Lowest voltage clamp
LVDS: Low Voltage Differential Signaling
LVECL: Low Voltage Emitter Coupled Logic
LVPECL: Low Voltage Positive Emitter Coupled Logic
LVTTL: Low Voltage Transistor-Transistor Logic
mA: Milliampere, or milliamp: 1/1000 of an Ampere. Ampere is the basic unit for measuring electrical current.
mAh: Milliamps/hour
Margining: Margining is a test procedure that determines the "safety margin." A parameter is varied to determine the device's sensitivity or ability to perform given a range of inputs. A large number of parts can be characterized to determine a safe range for the specification, to guarantee performance and yield.
Max. DNL (LSB): Maximum differential nonlinearly expressed in least significant bit(s).
Max. Hold Step (MV): When switching between sample mode and hold mode, charge injection from stray capacitance causes the maximum voltage of the hold capacitor to change.
Maximum Operating Temperature: The maximum temperature at which an instrument or sensor can be safely operated.
Maximum Power Rating: The maximum power in watts that a device can safely handle.
MCM: Multi-Chip Module (MCM): An integrated circuit package that contains two or more interconnected chips.
Mean Temperature: The average of the maximum and minimum temperature of a process equilibrium.
MEMS: Micro Electronic Mechanical Systems, or microelectromechanical systems.
Metal Oxide Varistor (MOV): A Metal Oxide Varistor (or surge-suppressor) is a discrete electronic component that diverts excessive voltage to the ground and/or neutral lines.
MHz: Megahertz (MHz): Measurement of frequency -- million cycles per second.
mm: Millimeter(s).
MOSFET: Metal-oxide semiconductor field-effect transistor; metal-oxide silicon field-effect transmitter. ms: Millisecond(s).
Multiplex: A technique which allows different input (or output) signals to use the same lines at different times, controlled by an external signal. Multiplexing is used to save on wiring and I/O ports.
mV: A millivolt (mV) is 1/1000 of a volt.
mW: Milliwatt(s).
MW: Megawatt(s).
nA: Nanoampere(s).
nV: Nanovolt (nV)
NiMH: Nickel metal hydride
NPR: Noise-power ratio
NRE: Nonrecurring engineering — one-time engineering costs associated with a project.
ns: Nanosecond(s)
NTC: Negative temperature coefficient
nW: Nanowatt(s)
NEMA-4: A standard from the National Electrical Manufacturers Association, which defines enclosures intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water.
NEMA-7: A standard from the National Electrical Manufacturers Association, which defines explosion-proof enclosures for use in locations classified as Class I, Groups A, B, C or D, as specified in the National Electrical Code.
NEMA-12: A standard from the National Electrical Manufacturers Association, which defines enclosures with protection against dirt, dust, splashes by non-corrosive liquids, and salt spray.
NEMA-Size Case: An older US case standard for panel meters, which requires a panel cutout of 3.93 x 1.69 inches. Noise: An unwanted electrical interference on the signal wires.
OC: Overcurrent
OEM: Original equipment manufacturer
Ohm: Resistance Unit.
Op amp: Operational amplifier: The ideal op amp is an amplifier with infinite input impedance, infinite open-loop gain, zero output impedance, infinite bandwidth, and zero noise. It has positive and negative inputs which allow circuits that use feedback to achieve a wide range of functions.
Using op amps, it's easy to make amplifiers, comparators, log amps, filters, oscillators, data converters, level translators, references, and more. Mathematical functions like addition, subtraction, multiplication, and integration can be easily accomplished.
Open Circuit: The lack of electrical contact in any part of the measuring circuit. An open circuit is usually characterized by rapid large jumps in displayed potential, followed by an off-scale reading.
OR: Combining two signals so that the output is on if either signal is present. This can be accomplished by an OR logic gate (two inputs, one output which is high if either input is).
Output to Input Ratio: The ratio between the sensed current and the output current of the amplifier.
Output Impedance: The resistance as measured on the output terminals of a pressure transducer.
Output Noise: The RMS, peak-to-peak (as specified) ac component of a transducer's dc output in the absence of a measurand variation.
Output: The electrical signal which is produced by an applied input to the transducer.
Overvoltage Protection: Overvoltage Protector (OVP) refers to a circuit that protects downstream circuitry from damage due to excessive voltage. An OVP monitors the DC voltage coming from an external power source, such as an off-line power supply or a battery, and protects the rest of the connected circuitry using one of two methods: a crowbar clamp circuit or a series-connected switch.
The crowbar short-circuits or clamps the supply line to limit the voltage, possibly triggering other forms of protection such as a fuse.
P-P: Peak-to-peak
pA: Picoampere(s)
PA: Power amplifier
PDI: Phase-detector input
PDIP: Plastic dual-inline package
PDJ: Pattern-dependent jitter
PDM: Pulse density modulation
PDO: Phase-detector output
PECL: Positive-referenced emitter-coupled logic
pF: Picofarad.
PFD: Phase/frequency detector
PFM: Pulse-Frequency Modulation: A pulse modulation technique in which the frequency is varied with the input signal amplitude. The duty cycle of the modulated signal does not change. Because it is always a square wave with changing frequency, PFM is also referred to as square-wave FM.
PG: Power Gain
PGA: Programmable Gain Amplifier: An amplifier whose gain can be varied by a separate input (usually a digital value).
PGA: Programmable logic array.
Phase Difference: The time expressed in degrees between the same reference point on two periodic waveforms.
Phase Proportioning: A form of temperature control where the power supplied to the process is controlled by limiting the phase angle of the line voltage.
Phase: A time based relationship between a periodic function and a reference. In electricity, it is expressed in angular degrees to describe the voltage or current relationship of two alternating waveforms.
PLCC: Leaded Chip Carrier, also called PLCC or Plastic Leaded Chip Carrier: A square surface mount chip package in plastic with leads (pins) on all four sides.
PLL: A phase-locked loop
PMIC: Power Management Integrated Circuit: Circuits used to regulate and control power.
PMM: Power-management mode.
Polarity: In electricity, the quality of having two oppositely charged poles, one positive one negative.
Positive Temperature Coefficient: An increase in resistance due to an increase in temperature.
Potential Energy: Energy related to the position or height above a place to which fluid could possibly flow.
Potentiometer: 1. A variable resistor often used to control a circuit. 2. A balancing bridge used to measure voltage.
Power Supply: A separate unit or part of a circuit that supplies power to the rest of the circuit or to a system.
PPM: Abbreviation for "parts per million," sometimes used to express temperature coefficients. For instance, 100 ppm is identical to 0.01%.
Printed Circuit Board: A printed circuit board, or PC board, or PCB, is a non-conductive material with conductive lines printed or etched. Electronic components are mounted on the board and the traces connect the components together to form a working circuit or assembly.
A PC board can have conductors on one side or two sides and can be multi-layer — a sandwich with many layers of conductors, each separated by insulating layers.
PROM: Programmable read-only memory
PTC: Positive Temperature Coefficient (PTC): When the resistance of a component rises with temperature, it is said to have a positive temperature coefficient.
PWM: 1. A method for using pulse width to encode or modulate a signal. The width of each pulse is a function of the amplitude of the signal.
2. A technique used to modulate the power delivered to a load. PWM Temperature sensor: Temperature sensor with digital, logic-level output. The output has a fixed frequency and the duty cycle varies with the measured temperature.
QFN: Quad, flat, no-lead" package.
QFP: Quad flat pack, a package type.
QS-9000: QS-9000 is the automotive quality standard superseded by ISO/TS16949:2002 specification for component suppliers to the automotive industry.
QSOP: Quarter small-outline package.
Quiescent: For an electronic circuit, a quiet state in which the circuit is driving no load and its inputs are not cycling. Most commonly used for the specification "quiescent current," the current consumed by a circuit when it in a quiescent state.
Rail-to-Rail Input: For an electronic circuit, a quiet state in which the circuit is driving no load and its inputs are not cycling. Most commonly used for the specification "quiescent current," the current consumed by a circuit when it in a quiescent state.
Rail-to-Rail Input/Output: The allowable input and output voltage ranges include the power-supply rails. RAM: Random access memory.
Random Jitter: Random jitter (RJ) includes all jitter components not defined as deterministic jitter (i.e., the jitter that is not related to the signal and known noise sources).
Recovery Time: The time for a sensor to return to baseline value after the step removal of the measured variable. Usually specified as time to fall to 10% of final value after step removal of measured variable.
Relay: A relay is an electromagnetic switching device consisting of an armature which is moved by an electromagnet to operate one or more switch contacts.
Relay (Mechanical): An electromechanical device that completes or interrupts a circuit by physically moving electrical contacts into contact with each other.
Relay (Solid State): A solid state switching device which completes or interrupts a circuit electrically with no moving parts.
Resistance Temperature Characteristic: A relationship between a thermistor's resistance and the temperature.
Resistance: Resistance, represented by the symbol R and measured in ohms, is a measure of the opposition to electrical flow in DC systems. Resistance is the voltage across an element divided by the current (R = V/I).
Resolution: The smallest detectable increment of measurement. Resolution is usually limited by the number of bits used to quantize the input signal. For example, a 12-bit A/D can resolve to one part in 4096 (2 to the 12 power equals 4096).
Resonant Frequency: The measurand frequency at which a transducer responds with maximum amplitude.
Response Time (time constant): The time required by a sensor to reach 63.2% of a step change in temperature under a specified set of conditions. Five time constants are required for the sensor to stabilize at 600 of the step change value.
Response Time: The length of time required for the output of a transducer to rise to a specified percentage of its final value as a result of a step change of input.
Reverse Recovery Time: When switching from the conducting to the blocking state, a diode or rectifier has stored charge that must first be discharged before the diode blocks reverse current. This discharge takes a finite amount of time known as the Reverse Recovery Time, or trr. During this time, diode current may flow in the reverse direction.
RFI: Radio frequency interference.
RH: Relative humidity
Rheostat: A variable resistor.
Ripple Rejection: Ripple Rejection is the ability of an amplifier to maintain accurate output voltage despite AC fluctuations in the power supply
Rise Time: The time required for a sensor or system to respond to an instantaneous step function, measured from the 10% to 90% points on the response waveforms.
Room Conditions: Ambient environmental conditions under which transducers must commonly operate.
Root Mean Square (RMS): Square root of the mean of the square of the signal taken during one full cycle.
ROM: Read-only memory.
RTC: Real-time clock: Integrated circuit that contains a timer that supplies the time of day (and often, the date). An RTC generally contains a long-life battery to allow it to keep track of the time even when there is no power applied.
RTD: A Resistance Temperature Detector (RTD) is a device with a significant temperature coefficient (that is, its resistance varies with temperature). It is used as a temperature measurement device, usually by passing a low-level current through it and measuring the voltage drop. A thermistor is a common type of RTD.
Rx: Receive.
S: Siemen(s); Lower case – second(s).
S-Parameters: The reflection and transmission coefficients used in impedance matching between high-speed (RF) devices and transmission lines/traces.
SBGA: Super ball-grid array, a packaging technology.
Schottky Diode: A diode realized via a "Schottky-barrier junction" -- a metal-semiconductor junction -- rather than the P-N junction used by conventional semiconductor diodes. Schottky diodes are often chosen for their high switching speed and low forward voltage drop.
SCL: Serial clock line
SCLK: Serial clock.
Semiconductor: A substance that can act as an electrical conductor or insulator depending on chemical alterations or external conditions. Examples are silicon, germanium, and gallium arsenide.
Sense Resistor: A substance that can act as an electrical conductor or insulator depending on chemical alterations or external conditions. Examples are silicon, germanium, and gallium arsenide.
Signal detect (SD): An output that indicates when a signal is present. A form of Signal Strength Indicator.
Signal: An electrical transmittance (either input or output) that conveys information.
SMPS: Switch-Mode Power Supply.
Snubber: A device which suppresses voltage transients.
Software: Generally, programs loaded into a computer from external mass storage but also extended to include operating systems and documentation.
SOIC: Small outline integrated circuit, a packaging technology.
SOT: Small outline transistor
Source: A "voltage source" or "current source" is an idealized generator of voltage or current in a circuit. These sources can be AC or DC, controlled or constant.
Source Code: A non-executable program written in a high-level language. A compiler or assembler must translate the source code into object code (machine language) that the computer can understand and process.
Spectrum Analysis: Utilizing frequency components of a vibration signal to determine the source and cause of vibration.
Spectrum: The resolving of overall vibration into amplitude components as a function of frequency.
SRAM: Static RAM: RAM that does not require a clock to retain its contents.
SRF: Self-resonant frequency.
SSOP: Shrink small-outline package.
Stability: The quality of an instrument or sensor to maintain a consistent output when a constant input is applied.
Step-Up DC-DC: A switch-mode voltage regulator in which output voltage is higher than its input voltage.
Step Down DC DC: See Buck
Step Down Regulator: See Buck
Step Down Switcher: See Buck
Step-Down DC DC: See Buck
Surface Acoustic Wave (SAW): A sound wave that propagates along the surface of a solid and is contained within the solid. SAW devices typically combine compressional and shear components. In Wireless applications, SAW refers to a Surface Acoustic Wave band-pass filter, which exhibits much better out-of-band rejection, but has higher passband ripple and insertion loss.
Surface Mount Device (SMD): An electronic component that mounts on the surface of a printed circuit board (as opposed to "through-hole" components which have pins that are inserted into holes). SMDs typically allow more components per square centimeter of PC board, but their scale is such that hand assembly and prototyping may be difficult.
Surge Current: A current of short duration that occurs when power is first applied to capacitive loads or temperature dependent resistive loads such as tungsten or molybdenum heaters-usually lasting no more than several cycles.
T/R: Transmit/receive
T1: T1 is standard for digital transmission in the United States.
Tad: Total accumulated discharge (mA-hr)
TC: Temperature coefficient
Thermal Coefficient of Resistance: The change in resistance of a semiconductor per unit change in temperature over a specific range of temperature.
TC/IP: Transmission Control Protocol/Internet Protocol
Temperature Compensated Crystal Oscillator TCXO: A crystal oscillator that includes circuitry that compensates for temperature variations, to maintain a more constant frequency.
Time Division Duplex (TDD): The second variation of WCDMA especially suited to indoor environments where there is a need for high traffic density.
Time Division Multiplexing (TDM): A scheme in which numerous signals are combined for transmission on a single communications line or channel. Each signal is broken into many segments, each having very short duration.
TDR: Time-delay relay
Temperature: The average kinetic energy of the atoms or molecules of a body or substance, perceived as warmth or coldness. Measured in degrees Fahrenheit, Celsius, or Kelvin.
Temperature Comparator: An integrated circuit with a digital output that indicates whether a measured temperature is above or below a predetermined threshold.
Temperature Switch: An integrated circuit with a digital output that indicates whether a measured temperature is above or below a predetermined threshold.
TFT: Thin-film transistor
THB: Temperature/humidity bias
Total Harmonic Distortion (THD): A measure of signal distortion which assesses the energy that occurs on harmonics of the original signal. It is specified as a percentage of the signal amplitude.
Total Harmonic Distortion Plus Noise (THD+N): It is the sum of the two most important distortion components. THD is the distortion that occurs on harmonics of the original signal -- it is correlated with the signal. Noise is the more random, uncorrelated distortion. THD+N is their sum.
Thermal Control Circuit: Circuit to monitor and control the temperature of something. For example the integrated temperature controller in Intel's processors.
Thermal Management: The use of various temperature monitoring devices and cooling methods, such as forced air flow, within a processor or FPGA-based system, to control overall temperature of ICs and internal cabinet temperatures.
Thermal Monitor: The integrated thermal control system used in Intel's processor devices.
Thermal Shutdown: Deactivating a circuit when a measured temperature is beyond a predetermined value.
Thermistor: A temperature-dependent resistor with a high temperature coefficient, usually composed of sintered semiconductor material.
Thermocouple: A temperature sensor formed by the junction of two dissimilar metals. A thermocouple produces a voltage proportional to the difference in temperature between the hot junction and the lead wire (cold) junction.
Thermocouple Type Material
(ANSI Symbol)
J Iron/Constantan
K CHROMEGA®/ALOMEGA®
T Copper/Constantan
E CHROMEGA®/Constantan
R Platinum/Platinum 13% Rhodium
S Platinum/Platinum 10% Rhodium
B Platinum 6% Rhodium/Platinum30% Rhodium
G* Tungsten/Tungsten 26% Rhenium
C* Tungsten 5% Rhenium/Tungsten 26% Rhenium
D* Tungsten 3% Rhenium/Tungsten 150 Rhenium
*Not ANSI symbols.
Thermocouple: The junction of two dissimilar metals which has a voltage output proportional to the difference in temperature between the hot junction and the lead wires (cold junction)
Thermal Conductivity: The property of a material to conduct heat in the form of thermal energy. Thermostat: Circuit that indicates whether a measured temperature is above or below a particular temperature threshold or trip point. Used for thermal protection and simple temperature control systems.
Through-Hole: A method for mounting components on a printed circuit board (PCB) in which pins on the component are inserted into holes in the board and soldered in place.
TQFN: Thin version of the QFN package (the JEDEC "W" option) 0.8mm thick.
TQFP: Thin quad flat pack.
Transceiver: A device that contains both a transmitter and receiver.
Transconductance: The gain of a transconductance amplifier (an amp in which the a change in input voltage causes a linear change in output current). The basic gain of vacuum tubes and FETs is expressed as transconductance. It is represented with the symbol gm.
The term derives from "transfer conductance" and is measured in Siemens (S), where 1 Siemens = 1 ampere per volt. It was formerly measured as "mho" (ohm spelled backwards).
Transformer: An inductive electrical device for changing the voltage of alternating current.
Transistor: A basic solid-state control device which allows or disallows current flow between two terminals, based on the voltage or current delivered to a third terminal.
Usually built from silicon but can be constructed from other semiconductor materials. There are two major types: The FET (field-effect transistor) and the bipolar junction transistor (BJT).
Transmitter: A circuit that accepts signals or data in and translates them into a form that can be sent across a medium (transmitted), usually over a distance. The medium can be wireless or wired.
Transducer: A device (or medium) that converts energy from one form to another. The term is generally applied to devices that take physical phenomenon (pressure, temperature, humidity, flow, etc.) and convert it to an electrical signal.
Transient Vibration: A temporary vibration or movement of a mechanical system.
Tri-State: An output with three electrical states: One, zero, and "Hi-Z," or "open." The hi-Z state is a high-impedance state in which the output is disconnected, leaving the signal open, to be driven by another device (or to be pulled up or down by a resistor provided to prevent an undefined state).
Commonly used for a bus, in which any several devices can be selected. If the bus has a pull-down resistor, the tri-state arrangement achieves an OR function, dubbed "wired-OR."
True RMS: The true root-mean-square value of an AC or AC-plus-DC signal, often used to determine power of a signal. For a perfect sine wave, the RMS value is 1.11072 times the rectified average value, which is utilized for low-cost metering. For significantly non-sinusoidal signals, a true RMS converter is required.
trr: Reverse Recovery Time
TSOC: Thin small-outline C-lead
TSOP: Thin small-outline package
TSSM: Temperature sensor and system monitor
TSSOP: Thin shrink small-outline package.
TTC: Temperature conversion sample time
TTFC: Time remaining to full charge
TTIMD: Two-tone intermodulation distortion
TTL Unit Load: A load with TTL voltage levels, which will draw 40 µA for a logic 1 and -1.6 mA for a logic 0.
TTL-Compatible: For digital input circuits, a logic 1 is obtained for inputs of 2.0 to 5.5 V which can source 40 µA, and a logic 0 is obtained for inputs of 0 to 0.8 V which can sink 1.6 mA. For digital output signals, a logic 1 is represented by 2.4 to 5.5 V with a current source capability of at least 400 µA; and a logic 0 is represented by 0 to 0.6 V with a current sink capability of at least 16 mA.
TTL: Transistor-to-transistor logic. A form of solid state logic which uses only transistors to form the logic gates.
TUE: Total unadjusted error
TVM: Test vector monitor
Tx: Transmit
uA: Microampere, or microamp: A millionth of an Ampere. Ampere is the basic unit for measuring electrical current.
UART: Universal Asynchronous Receiver-Transmitter: An IC that converts parallel data to serial, for transmission; and converts received serial data to parallel data.
UI: Unit interval.
UL: Underwriters Laboratories, Inc. An independent laboratory that establishes standards for commercial and industrial products.
UMTS: Universal Mobile Telecommunications System.
Universal Serial Bus (USB): A standard port that enables you to connect external devices (such as digital cameras, scanners, keyboards, and mice) to computers. The USB standard supports data transfer at three rates: low speed (1.5MBps), full speed (12Mbps) and high speed (480 MBps).
Undershoot: The difference in temperature between the temperature a process goes to, below the set point, after the cooling cycle is turned off and the set point temperature.
Undershoot: The difference in temperature between the temperature a process goes to, below the set point, after the cooling cycle is turned off and the set point temperature.
URL: web address.
UV: Ultraviolet.
UVLO: Undervoltage lockout.
V-s: Volt-second(s)
Vcc: The supply voltage for a circuit is often given as V plus a double-letter suffix. The double letter is usually related to the lead of the transistors that are commonly connected to that supply or to a resistor that connects to that supply.
VCO: Voltage-Controlled Oscillator: An oscillator device in which output frequency is proportional to its input voltage.
VCSEL: Vertical cavity-surface emitting laser.
VCTCXO: Voltage Controlled, Temperature Compensated Crystal Oscillator: A TCXO which offers the ability to control the oscillation frequency with an analog voltage.
Voltage Controlled Crystal Oscillator (VCXO): An oscillator that uses a crystal to establish its frequency but will vary its frequency as an analog control voltage varies.
VFO: Variable-frequency oscillator.
VGA: Variable-gain amplifier.
VLF: Very-low frequency
VLIF: Very-low intermediate frequency
Very large-scale integration (VLSI): This refers to an IC or technology with many devices on one chip. The question, of course, is how one defines "many."
Very High Data-Rate Digital Subscriber Line (VSDL): A method for delivering high-speed digital services on the standard twisted pair used for voice phone lines. VDSH operates at data rates from 12.9Mbps to 52.8Mbps.
Voice over Internet Protocol (VoIP): Method for transmission of voice (or fax) calls over the Internet.
Volt (or Volts): Unit of measure for electromotive force (EMF), the electrical potential between two points. An electrical potential of 1 volt will push 1 ampere of current through a 1-ohm resistive load.
Volt-Ampere: A volt-ampere (VA) is the voltage times the current feeding an electrical load. A kilovolt-ampere (kVA) is 1000 volt-amperes.
Electrical power is measured in watts (W): The voltage times the current measured each instant. In a direct current system or for resistive loads, the wattage and VA measurements will be identical. But for reactive loads, the voltage and current are out of phase and the volt-ampere spec will be greater than the wattage.
Voltage Regulator: A circuit which is connected between the power source and a load, which provides a constant voltage despite variations in input voltage or output load.
Vp-p: Peak-to-peak voltage.
VRD: Voltage Regulator Down, an Intel standard for voltage regulators which are "down" on the mother board.
VRM: Voltage Regulator Module
Vss: See Vcc
VSWR: VSWR (Voltage Standing Wave Ratio or, occasionally, Vertical Standing Wave Ratio), is a measure of how efficiently radio-frequency power is transmitted from a power source, through a transmission line, into a load (for example, from a power amplifier through a transmission line, to an antenna).
W: Watt (W) is the unit for measuring power. In physics terms, one watt is one Joule of energy transferred or dissipated in one second. Electrical power is calculated as:
Watts = Volts x Amps x Power Factor
The power factor can be disregarded for DC circuits or for AC circuits with a resistive load (it is 1 in those situations).
Wafer: Semiconductor manufacturing begins with a thin disk of semiconductor material, called a "wafer." A series of processes defines transistors and other structures, interconnected by conductors to build the desired circuit.
The wafer is then sliced into "dice" which are mounted in packages, creating the IC.
Wafer Fab: Semiconductor processing facility which turns wafers into integrated circuits. A typical wafer fab employs a series of complex steps to define conductors, transistors, resistors, and other electronic components on the the semiconductor wafer. Imaging steps define what areas will be affected by subsequent physical and chemical processes.
WAN: Wide Area Network.
Watchdog: A feature of a microprocessor supervisory circuit that monitors software execution in a microprocessor or microcontroller. It takes appropriate action (assert a reset or nonmaskable interrupt) if the processor gets stuck in an infinite execution loop.
WDI: Watchdog input.
WDPO: Watchdog pulse output.
WE: Write enable.
Watt Density: The watts emanating from each square inch of heated surface area of a heater. Expressed in units of watts per square inch.
Wheatstone Bridge: A network of four resistances, an emf source, and a galvanometer connected such that when the four resistances are matched, the galvanometer will show a zero deflection or "null" reading.
WR-RD: Write-read.
Crystal clock oscillator (XCO): An oscillator that relies on a crystal for its frequency reference. A piezoelectric crystal oscillates at a very stable frequency.
Xfmr: See Transformer.
Zero Power Resistance: The resistance of a thermistor or RTD element with no power being dissipated.
Z: Impedance.
ZVC: Zero voltage crossing
Zero Voltage Switching (ZVS): The making or breaking of circuit timed such that the transition occurs when the voltage wave form crosses zero voltage; typically only found in solid state switching devices.
