Alphabetical Listing of all Electrical Engineering Glossary Terms and Definitions

More info:

• 1-Wire Memory Products
• 1-Wire Interface Solutions
• 1-Wire SW Tools

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

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:

• Application Note/Tutorial: Filter Basics: Anti-Aliasing
• The Basics of Anti-Aliasing: Using Switched-Capacitor Filters
• Mathematical Basics of Band-Limited Sampling and Aliasing
• Folded-Frequency Calculator

2. Amplifier

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

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.

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)?.

Also see:

• Application Note/Tutorial: Filter Basics: Anti-Aliasing
• The Basics of Anti-Aliasing: Using Switched-Capacitor Filters

See: Maxim ASIC services.

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 0.0201 inch or 0.511 mm. 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.

Example: An AM broadcast radio channel in the US has a bandwidth of 10kHz, meaning that it occupies a 10kHz-wide band, such as the frequencies from 760kHz to 770kHz.

2. The amount of data a digital channel or line can handle, expressed in bits per second (bps), kilobits per second (kbps), baud, or a similar measure.

A femto base station is a smaller, personal base station which might cover a home or building and connect via a DSL Internet connection.

Contrast to the other main transistor type, the FET, in which the ouput current is controlled by input voltage (rather than by input current).

Applies to mechanical systems (e.g. that use relays or manual switches) and to solid-state analog multiplexers and switches.

This can double the voltage swing at the speaker, compared to a speaker that is connected to ground. The ground-tied speaker can have a swing from zero to the amplifier's supply voltage. A BTL-driven speaker can see twice this swing because the amplifier can drive either the + terminal of the speaker or the — terminal, effectively doubling the voltage swing.

Since twice the voltage means four times the power, this is a major improvement, especially in applications where battery size dictates a lower supply voltage — e.g. automotive or handheld applications.

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.

Note: A customer asked the origin of the term and no one seems to know! A buck regulator is a step-down regulator, as opposed to boost. We think it's an American term — in England it was always "step-down."

Buck means to resist or reduce (as in "buck the trend"), and hence was used to denote a step-down. Conveniently, it alliterates with the opposite, a boost regulator.

2) The maximum short-term throughput which a device is capable of transferring data.

Often misspelled "buss."

2. Also see Y/C

Maxim offers both regulated and non-regulated charge pumps, as well as ICs with on-board charge pumps to boost internal voltages.

See: DC-DC Converter Tutorial

2. Encoding element, in Direct-Sequence Spread Spectrum systems.

This is achieved by biasing both transistors so they conduct when the signal is close to zero (the point where class B amplifiers introduce non-linearities). The transistors transition to class B operation for large excursions.

So, for small signals both transistors are active, acting like a class A amplifier. For large signal excursions, only one transistor is active for each half of the waveform, acting like a class B amplifier.

Class B amplifiers are much more efficient than class A amplifiers, but have high distortion due to the crossover point when the two transistors transition from on to off.

Class C amps are very efficient because the transistors are off most of the time and when they are on, they are in full conduction. They deliver high distortion and are often used in RF circuits, where tuning circuits restore some of the original signal and reduce distortion. They are also used in low-fidelity applications where the distortion is not important, such as a siren speaker driver.

Class D amplifiers are highly efficient (often up to 90% or higher) since the output transistors are either fully turned on or off during operation. This completely eliminates the use of the linear region of the transistor which is responsible for the inefficiency of other amplifier types. Modern Class D amplifiers achieve fidelity comparable to class AB.

Class G amplifiers are more efficient than class AB amplifiers since they use the maximum supply voltage only when required, while a class AB amplifier always uses the maximum supply voltage.

Class H amplifiers are generally more complex than other designs, with extra control circuitry required to predict and control the supply voltage.

• powered up (power applied)
• powered down (power removed)
• brought out of shutdown (power applied previously)
• forced into shutdown (power still applied)

For more information and illustrations, see:

• "Jitter Overview" in HFAN-04.3.0: Jitter Specifications Made Easy; and
• An Introduction to Jitter in Communications Systems.

See the tutorial, Understanding Common-Mode Signals.

Examples: In NTSC television, a 3.579545MHz color subcarrier is quadrature-modulated by two color-difference signals and added to the luminance signal. The PAL television standard uses a subcarrier frequency of 4.43362MHz.

See: Video Basics

In an ideal differential amp, the common-mode element is cancelled out, since the differential (+ and -) inputs should subtract out the identical components. A measurement of the actual ability to do this is called the Common Mode Rejection Ratio, or CMRR.

See the tutorial, Understanding Common-Mode Signals.

A signal is passed through a non-linear transformation prior to transmission. A reverse of this transformation occurs at reception. The transformation is such that quiet portions are boosted and loud portions reduced. Noise is reduced because the quiet signals are louder, compared to the noise in the transmission channel.

Used in digital, PCM, transmissions as well as analog applications. Dolby is a common example of a compander-based noise reduction system.

When described that way, the comparator resembles a 1-bit ADC.

A simple comparator can be achieved using an op amp without negative feedback. Its high voltage gain enables it to resolve very small differences in input voltage. But op amps used this way are generally slower than comparators and lack special features, such as hysteresis and internal references.

Application Note 886: Selecting the Right Comparator goes into more details on how comparators work, their specifications, common comparator features, and how to select a comparator that best fits your needs.

It is usually achieved by an SCR or other silicon device, or by a mechanical shorting device.

Probably named for the concept of using a big metal bar to mechanically provide the short circuit, as might be used done in a high-current application; or from the appearance of a crowbar circuit's I-V curve.

See: Protection and Isolation products.

Also see:

• A Simple ADC Comparison Matrix
• Understanding SAR ADCs
• Understanding Flash ADCs

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.

Decibels are also used to describe a signal level by comparing it to a reference level. The reference is usually defined as 0dB and the dB value of the signal is 10 times the log of the signal's power over that of the reference. A letter is sometimes added to signify the reference. For instance, dBm is relative to 0 dBm = 1mW.

See: DC-DC Converter Tutorial

In the most straightforward realization, a digitized sample of the waveform is stored and the values are clocked out to a D/A converter. Varying the clock rate changes the frequency. Variations in rate and changes to a gain factor can modulate the signal.

More: Switch Bounce and Other Dirty Little Secrets

For more information and illustrations, see:

• "Jitter Overview" in HFAN-04.3.0: Jitter Specifications Made Easy; and
• An Introduction to Jitter in Communications Systems.

Examples: RS-422, RS-485, professional audio signal standards (especially for microphones), the signal lines employed by Ethernet, and the standard twisted-pair analog telephone (POTS) line.

Also see the tutorial, Understanding Common-Mode Signals.

See: High-Brightness LED Drivers

This process is reserved for package types which are especially susceptible to moisture intrusion. Maxim/Dallas devices with MSL (Moisture Sensitivity Level) of 2 or higher require drypack. A part-number suffix of -D, +D, or #D at the end of the part number denotes products which ship with drypack. There is no price adder associated with drypacking products with MSL 2 or above.

See: "An Introduction to Direct-Sequence Spread-Spectrum Communications".

Each digit is encoded as the sum of two sine wave bursts, of different frequencies. The two-tone method was chosen because it can be reliably distinguished from voice and normal phone conversations are highly unlikely to falsely trigger the DTMF receiver.

DTMF was the basis for "TouchTone" (a former trademark of AT&T), the pushbutton system that replaced mechanical rotary dial telephones.

(Maxim Integrated Products, Inc. trademarked term.)

This low-frequency signal is then further divided by the main counter to the desired channel-spacing frequency which is then fed to the phase detector to form the closed feedback loop in frequency synthesizers.

Often, the computer is relatively invisible to the user, without obvious applications, files, or operating systems. Examples of products with invisible embedded systems are the controller that runs a microwave oven or the engine control system of a modern automobile.

See: EMI Reduction Solutions page.

See the following application notes that describe how ESD is generated, how it damages electronic systems, human body and machine models for testing, IEC compliance levels, and design approaches.

• App note: Maxim Leads the Way in ESD Protection
• App note: ESD Protection for I/O Ports
• App note: Switch Bounce and Other Dirty Little Secrets

A capacitor can be modeled as an ideal capacitor in series with a resistor and an inductor. The resistor's value is the ESR.

EVKIT: Part number suffix used for Maxim Evaluation Kits.

Dallas Semiconductor, now owned by Maxim, used the term "development kit."

See the list of Maxim Evaluation Kits and EVKit software.

EVSYS: Suffix used for Maxim Evaluation System part numbers.

2. f in lower case is the standard abbreviation for femto, a metric prefix for 10 to the -15.

A femto base station benefits the service provider because it offloads cell tower traffic. Subscribers benefit from superior signal strength, due to the proximity of the unit -- especially where a cellular signal is weak or not available.

Femto base stations augment the normal network and replicates the usual telecommunications infrastructure. Connection to the cell phone network is provided by VoIP over the Internet.

More on femto base stations and information on Maxim's femto base station chipsets.

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.

Contrast with FTTN (fiber-to-the-node) which uses fiber up to a node outside the home and uses copper to bring the data into the home.

There are two technologies for delivering broadband: Fiber-to-the-node (FTTN) uses fiber to bring data to a node and uses copper to bring the data into the home. Fiber-to-the-home (FTTH) brings fiber all the way into the home.

Gain error is usually expressed in LSB or as a percent of full-scale range. Gain error can be calibrated out with hardware or in software. Gain error is the full-scale error minus the offset error.

See: Application Note 641: ADC and DAC Glossary

Most commonly applied to make a light-emitting device, such as a display, match the human eye's brightness curve. In other terms: A gamma correction function can be used to alter the luminance (light intensity) of a display such that its brightness (the human-perceived values) looks correct.

2. A basic logic element (e.g. AND, OR, NOT, NAND, NOR, XOR, etc.).

Bluetooth uses GFSK.

See: High-Brightness LED Drivers and Solutions

See the following application notes that describe how ESD is generated, how it damages electronic systems, human body and machine models for testing, IEC compliance levels, and design approaches.

• App note: Maxim Leads the Way in ESD Protection
• App note: ESD Protection for I/O Ports

See: Maxim Solutions for HVAC designers.

Abbreviated from "in-phase/quadrature-phase" which refers to the two carrier signals' phase relationship.

2. I_Q (Q should be subscripted but sometimes printed as "IQ" without subscripting): Quiescent current: The current consumed when a circuit is in a quiet state, driving no load and if appropriate, with its inputs not cycling.

3. Intelligence quotient, a measure in which electrical engineers invariably excel.

SMBus is electrically similar — see Comparing the I2C Bus to the SMBus.

See also: I²C Data Converters, and do a site search for I2C to find other I2C articles and products.