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Glossary Terms and Definitions Beginning with the Letter d

0-9

D-Pot	See Digital Pot
D/A	See D/A Converter
D/A Converter	Digital-to-analog converter (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.
DAC	See D/A Converter
Daisy Chain	A method of propagating signals along a bus in which the devices are connected in series and the signal passed from one device to the next. The daisy chain scheme permits assignment of device priorities based on the electrical position of the device on the bus.
Daisy-Chain	See Daisy Chain
Dallastat	Trademark for Dallas Semiconductor's line of digital rheostats (digital potentiometers). (Dallas Semiconductor is a subsidiary of Maxim Integrated Products.)
DAQ	See Data Acquisition System
DAS	See Data Acquisition System
Data Acquisition System	See DAQ
Data Converter	A/D or D/A converter: An electronic circuit that converts analog signals to digital, or vice-versa. An analog signal is a continuously varying voltage or current. Its digital counterpart is a stream of digital numbers, each representing the amplitude of the analog signal at a moment in time. Also see: A Simple ADC Comparison Matrix Understanding SAR ADCs Understanding Flash ADCs
Data Management Language	See DML
Data Manipulation Language	See DML
Data Over Cable Service Interface Specification	See DOCSIS
Daylight Running	See DRL
Daytime Running Lamp	See DRL
Daytime Running Light	See DRL
dB	Decibels: A method for specifying the ratio of two signals. 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.
dBA	See A-Weighting
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.
DBS	Direct Broadcast Satellite: A system which broadcasts directly from satellite to the subscriber (end user). Prominent examples in the US are DirecTV and Dish network.
DC	Direct current
DC-DC Controller	See DC-DC Controllers
DC-DC Controllers	A DC-DC converter (switch-mode power supply) in which the power switch (usually a power MOSFET) is external to the IC.
DC-DC Converter	See DC-DCs
DC-DCs	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. See: DC-DC Converter Tutorial
DC/DC	See DC-DCs
DCE	Data communications equipment; interchangeable with DTE
DCM	Discontinuous-conduction mode
DCR	Direct conversion receiver
DCS	Digital Cellular System: Any cellular phone system that uses digital (e.g. TDMA, GSM, CDMA).
DDI	Digital data input
DDJ	Data-dependent jitter
DDR	See DDR Memory
DDR Memory	Double Data Rate Synchronous DRAM: A clock is used to read data from a DRAM. DDR memory reads data on both the rising and falling edge of the clock, achieving a faster data rate. Often used in notebook computers because it also consumes less power.
DDR RAM	See DDR Memory
DDR-SDRAM	See DDR Memory
DDRAM	See DDR Memory
DDRD	Data direction register D
DDS	DDS (direct digital synthesis) is a method for digitally generating analog waveforms, such as sine waves (modulated or not) or arbitrary waveforms. 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.
Debounce	Electrical contacts in mechanical pushbutton switches often make and break contact several times when the button is first pushed. A debouncing circuit removes the resulting ripple signal, and provides a clean transition at its output. More: Switch Bounce and Other Dirty Little Secrets
Debounced	See Debounce
Debouncing	See Debounce
Decibel	See dB
DECT	Digital European cordless telephone
Delay Line	See STC
Dense Wave Division Multiplexing	See DWDM
Design for Testability	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 diagnotics, test modes, and scan design.
Deterministic Jitter	Reproducible jitter within a given system, under controlled conditions. Also known as bounded jitter. 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.
Development Kit	See Evaluation Kit
DFE	Decision feedback equalization
DFMEA	Design Failure Mode and Effects Analysis (DFMEA) is a method for evaluating a design for robustness against potential failures.
DFT	See Design for Testability
DG	Differential gain
Differential	See Differential Signaling
Differential Non-Linearity	See DNL
Differential Nonlinearity	See DNL
Differential Remote Output Sensing	Uses a Kelvin connection at a remote location to sense the output voltage and better control the voltage at that point.
Differential Signaling	Most electrical signals are single-ended, comprised of a single wire and ground. Differential signals use two wires which are the inverse of each other -- when one swings positive, the other swings negative in equal magnitude. The receiving circuit looks only at the difference between the two, ignoring any common-mode voltage. This "push-pull" arrangement reduces the impact of electrical interference because external noise will affect both wires equally and the common-mode rejection will ignore the noise. 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.
Digipot	See Digital Pot
digital amplifier	See Class D
Digital Cellular System	See DCS
Digital Fan Control	See Fan Controller - PWM
Digital Log Pot	Digital logarithmic potentiometer.
Digital Multimeter	See DMM
Digital Pot	Digital potentiometer: A solid-state device that emulates a mechanical potentiometer, it is usually controlled via a simple interface.
Digital Potentiometer	See Digital Pot
Digital Resistors	See Digital Pot
Digital Subscriber Line	See DSL
Digital Video Broadcast	See DVB
Digital-To-Analog Converter	See D/A Converter
DIO	Data input/output
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 dioides can also be realized using vacuum tube, point-contact, metal-semiconductor junction (Schottky), and other technologies.
DIP	Dual Inline Package. Also: PDIP = plastic DIP; CDIP = ceramic DIP
Direct Broadcast Satellite	See DBS
direct digital synthesis	See DDS
Direct Memory Access	See DMA
Direct-Sequence Spread Spectrum	See DSSS
Distortion	In systems that handle electrical signals, distortion is a generally unwanted change in the signal. Not all signal alterations are considered distortion. For instance, a uniform delay or a linear attenuation or amplification would generally not be considered distortion.
Dithering	A common technique to improve digitizing when quantization noise (quantization error/noise) can no longer be treated as random. A small amount of random noise is added to the analog input signal. This added noise causes the digital output to randomly toggle between two adjacent codes, thereby avoiding thresholding effect.
DIU	Digital interface unit
DJ	See Deterministic Jitter
DLC	Double-layer capacitor
Dlog Pot	See Digital Log Pot
DMA	Direct Memory Access: A scheme which reads or writes data directly to memory, bypassing the processor and the processor bus.
DML	Data Manipulation Language (or Data Management Language): A language that allows data to be manipulated in a database. In SQL, commands such as DELETE and INSERT are DML commands.
DMM	Digital Multimeter: Measuring instrument or VOM (e.g. voltage, resistance, current) with a digital display.
DMMs	See DMM
DMP	See Dual-Modulus Prescaler
DMR	Digital microwave radio
DMT	Discrete multitone data transmission
DNL	Differential Nonlinearity: A specification that appears in data-converter datasheets. In an ideal D/A converter, incrementing the digital code by 1 changes the output voltage by an amount that does not vary across the device's permitted range. Similarly, in an A/D, the digital value ramps smoothly as the input is linearly swept across its entire range. DNL measures the deviation from the ideal. An ideal converter has the code exactly the same size, and a DNL of 0 (zero).
DOCSIS	Data Over Cable Service Interface Specification: A standard for delivering data over cable TV systems, typically for subscriber Internet access services.
Double Data Rate Synchronous DRAM	See DDR Memory
Doublers	See Voltage Doubler
Down Converter	See Down Converters
Down Converters	A device which provides frequency conversion to a lower frequency, e.g. in digital broadcast satellite applications.
Downconverter	See Down Converters
DP	Differential phase; also decimal place
DPAK	Discrete packaging
DPD	Digital phase detector
DPDT	See SPST
DPH	Data pointer high
DPL	Data pointer low
DPM	Digital panel meter
DPOT	See Digital Pot
DPS	Data pointer select
DPST	Double-pole/single-throw
DPWM	Digitally adjusted pulse-width modulation
DQPSK	Differential quadrature phase-shift keying
Drain	One of the three terminals that comprise a FET. A voltage on the gate controls the current flow between the source and drain.
DRAM	Dynamic RAM: Random-Access Memory that uses a continuous clock. Unlike SRAM, when DRAM is no longer clocked, its data is lost.
DRC	Design-rule checking
DRL	Daytime Running Lamps (DRLs) are white lights mounted on the front of an automobile. Mandated in many countries, they automatically switch on when the key is turned and are intended for daytime use, to increase the visibility of the automobile. They are typically built with LEDs. See: High-Brightness LED Drivers
Drypack	Drypack is a method for packing integrated circuits in a moisture-free environment. The device is baked and immediately sealed in a vacuum-sealed bag. This process is reserved for package types which are especially susceptible to moisture intrusion. Maxim 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.
DSL	A mechanism for providing high-speed digital communications (e.g. Internet access) over a standard phone line.
DSLAM	Digital Subscriber Line Access Multiplexer: a device which takes a number of ADSL subscriber lines and concentrates these to a single ATM line.
DSSP	Digital-sensor signal processor
DSSS	Direct-Sequence Spread Spectrum: A transmission technology used in WLAN (wireless LAN) transmissions where a data signal at the sending station is combined with a higher data-rate bit sequence, or chipping code, that divides the user data according to a spreading ratio. See: "An Introduction to Direct-Sequence Spread-Spectrum Communications".
DTB	Digital terrestrial broadcasting
DTE	Data terminal equipment; interchangeable with DCE
DTMF	Dual Tone Multiple Frequency (DTMF) is a signaling method developed by Bell Labs for sending telephone dialing information over the same analog, voice-quality phones lines that carry voice. 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.
Dual Mode	Two modes of operation. Examples: In power circuits, the IC can deliver either a fixed 5V or an adjustable 1.3V to 16V source. In cellular phones, the IC operates in FM or CDMA mode, AMPS or TDMA mode, etc. (Maxim Integrated Products, Inc. trademarked term.)
Dual Phase Controller	Switching regulator that employs dual-phase technique to reduce output noise and boost output current capability.
Dual Tone Multiple Frequency	See DTMF
Dual-Band	Dual-band refers to the capability of GSM network infrastructure and handsets to operate across two frequency bands.
Dual-Modulus Prescaler	A Dual-Modulus Prescaler (DMP) is an important circuit block used in frequency synthesizers to divide the high-frequency signal from the voltage controlled oscillator (VCO) to a low-frequency signal by a predetermined divide ratio, either (N+1) or N, which is controlled by a swallow counter. 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.
DVB	Digital Video Broadcast is a name for digital TV.
DVM	Digital voltmeter
DWDM	Dense Wave Division Multiplexing: 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.
DXC	Digital cross-connect
Dynamic RAM	See DRAM
Dynamic Range	The range, in dB, between the noise floor of a device and its defined maximum output level.