Glossary Terms and Definitions Beginning with the Letter A

A See Ampere
A to D See A/D Converter
A-D See A/D Converter
A-h See Ampere-hour
A-weighted dB levels See A-Weighting
A-Weighting A-weighting is a standard weighting curve applied to audio measurements, designed to reflect the response of the human ear.

Sound-pressure levels derived using A-weighting are denoted by "dBA," or A-weighted dB levels.

A/D See A/D Converter
A/D Converter Analog to digital. Specifically: A/D converter, a circuit that converts analog signals into a stream of digital data.
A/D Mux See ADM
Accelerometer A sensor or transducer for measuring acceleration.
Access Point Base Station See Femto Base Station
ACPI Advanced Configuration and Power Interface: An industry-standard specification (co-developed by Hewlett-Packard, Intel, Microsoft, Phoenix, and Toshiba) for operating-system-directed power management for laptop, desktop, and server computers. A replacement for APM.
ACPR Adjacent (alternate)-channel power ratio
ACR Accumulated current register
ADC See A/D Converter
Add-Drop Mux See ADM
ADM 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.
ADPCM Adaptive Differential Pulse Code Modulation: A compression technique that encodes only the difference between sequential samples.
ADS Analog design system
ADSL Asymmetric Digital Subscriber Line: 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).
Advanced Configuration And Power Interface See ACPI
Advanced Mobile Phone System See AMPS
Advanced Power Management See APM
Advanced Product Quality Planning See APQP
AEC-Q100 A qualification test sequence for integrated circuits developed by the AIAG automotive organization.
AECQ100 See AEC-Q100
AFE Analog Front End: The analog portion of a circuit which precedes A/D conversion.
AGC Automatic Gain Control: A circuit that modulates an amplifier's gain, in response to the relative strength of the input signal, in order to maintain the output power.
Ah Ampere-hour(s): A measure of battery capacity. A 4Ah battery could, for instance, deliver 1A for 4 hours, 1/2A for 8 hours, etc.
Air Discharge A method for testing ESD-protection structures in which the ESD generator is discharged through an air gap between the generator and the device under test (DUT).
Air Gap Discharge See Air Discharge
Air-Gap Discharge Method See Air Discharge
AIS Alarm indication system
AISG The Antenna Interface Standards Group (AISG) creates open specifications for antenna-line control and monitoring for 3G systems.

Source: AISG website

alias See Aliasing
Aliasing In A/D conversion, the Nyquist principle states that the sampling rate must be at least twice the maximum bandwidth of the analog signal. If the sampling rate is insufficient, then higher-frequency components are "undersampled" and appear shifted to lower-frequencies. These frequency-shifted components are called aliases.

The frequencies that shift are sometimes called "folded" frequencies because a spectral plot looks like it was folded to superimpose the higher frequency components over the sub-Nyquist portion of the band.

Also see:

Alternator An electromechanical device that converts mechanical power into AC electrical power.

Typically, a magnet spins inside a coil, inducing alternating current in the windings. The magnet can be a permanent magnet, an iron rotor in which a magnetic field is induced, or an electromagnet powered by an externally applied current.

AM Amplitude Modulation: A modulation method in which the carrier amplitude changes with the input signal amplitude.
Ambient Sensor See Ambient Temperature Sensor
Ambient Temperature Temperature of the air surrounding a component.
Ambient Temperature Sensor Temperature sensor used to measure the temperature of the air that surrounds a component (the ambient temperature).
American National Standards Institute See ANSI
American Wire Gauge See AWG
AMLCD Active-matrix liquid-crystal display
Amp 1. Ampere

2. Amplifier

amp-hour See Ampere-hour
Ampacity The amount of current a conductor can carry without exceeding its specified temperature, in amperes.
Ampere Ampere(s), the unit of electrical current. Current is defined as the amount of charge that flows past a give point, per unit of time.

The symbol I is used for current in equations and A is the abbreviation for ampere.

Ampere-hour A measure of charge (or current flow over time).

  • One ampere-hour (or amp-hour or Ah) is a current of one ampere flowing for one hour. The amount of charge transferred in that hour is 3,600 coulombs (ampere-seconds).
  • A milliampere-hour (mAh or milliamp-hour) is a thousandth of an amp-hour.
  • An ampere-second (A-s or amp-second) is an amp supplied for one second.

A common use of the term is rating energy storage device capacity, especially rechargeable batteries. For example, a 12-volt, 7Ah rechargeable battery used in an alarm system will supply an amp at the rated voltage range for seven hours, 2 amps for 3.5 hours, etc. If my alarm consumes 250mA, this battery would operate the system for 28 hours.

ampere-second See Ampere-hour
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).
Amplifier Class Amplifier circuit types are divided into "classes" which describe whether the amplifier operates in a linear or switching mode, and any techniques used to restore linearity of output.
Amplitude Modulation See AM
AMPS Advanced Mobile Phone System: An analog only, 1G standard that operates in the 800MHz to 900MHz frequency band. It is still widely used in the United States.
AMR Automatic Meter Reading: A system installed to read a utility meter remotely.
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 Fan Controller See Fan Controller - Linear
Analog Front End See AFE
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.

Most commonly implemented using CMOS technology integrated circuits. Maxim makes hundreds of examples. See the Analog Switch and Multiplexer Product Line page.

Also see What is a Transmission Gate (Analog Switch)?.

Analog Temperature Sensor Temperature sensor with a continuous analog voltage or current output that is related, usually linearly, to the measured temperature.
Analog to Digital See A/D Converter
analogue See Analog
AND Combining two signals so that the output is on if both signals are present. This can be accomplished by an AND logic gate (two inputs, one output which is high if both inputs are).
ANSI American National Standards Institute
Antenna Interface Standards Group See AISG
anti-alias See Anti-Aliasing
Anti-Aliasing 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.

Also see:

APC Automatic Power Control: Feature in laser drivers (such as the MAX3669) that uses feedback from the laser to adjust the drive, to keep the laser's output constant.
APD Avalanche Photo Diode: 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.
API Application program interface: A software layer that allows a system to be programmed via a defined set of commands.
APM Advanced Power Management: Power management standard for computers that provides five power states: Ready, Stand-by, Suspended, Hibernation, Off.
APON ATM (-based) passive optical network
APQP Advanced Product Quality Planning. System developed by the AIAG automotive organization to communicate common product quality planning and control plan guidelines for suppliers to the automotive industry.
Arrhenius See FIT
Arrhenius/FIT Rate See FIT
ASCII American Standard Codes for Information Interchange
ASIC Application-specific integrated circuit.

See: Maxim ASIC services.

Asymmetric Digital Subscriber Line See ADSL
ATE Automatic test equipment; automated test equipment. See: "Maxim ATE Solutions."
ATM Asynchronous transfer mode
Audio Taper See Taper
Auto Shutdown A feature in EIA-232 interface devices which puts the IC into a low-power shutdown mode when no signal is present on the EIA-232 bus.
Auto Shutdown + See Autoshutdown Plus
Autoclave Test See Pressure Cooker Test
Automatic Gain Control See AGC
Automatic Meter Reading See AMR
Automatic Power Control See APC
AutoShutdown See Auto Shutdown
Autoshutdown Plus A feature in EIA-232 interface devices which puts the IC into a low-power shutdown mode when no signal is present on the bus or the transmitter inputs.
AutoShutdown+ See Autoshutdown Plus
Autotransformer An autotransformer is a transformer that uses a common winding for both the primary and secondary windings. Essentially an inductor with a center-tap, an autotransformer is often used in power-supply boost-converter applications to achieve a higher output voltage, while limiting the peak flyback voltage seen by the power switch.
Avalanche Photo Diode See APD
Avalanche Photodiode See APD
AWG 1. Arbitrary waveform generator

2. American Wire Gauge: 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 0.0201in or 0.511mm. Also called the Brown and Sharpe Wire Gauge.

Note that steel wire is measured by a different gauge. AWG only applies to wire used to conduct electricity.