# What are abbreviations used in electrical engineering?

This question is meant to be a glossary of abbreviations used in electrical engineering.

Some abbreviations are very common and universal, and are therefore acceptable to use on this site. Others are quite localized or pet abbreviations used by individuals without a wide following, so are not acceptable on this site. One purpose of this question is to list all abbreviations so that others have a chance to decode them if encountered, but thru voting also show which ones are acceptable to use in a wide international context or not.

So here are some rules to make this question work:

1. Each answer must only be for ONE abbreviation.

2. This will be community wiki, so only ONE answer for each abbreviation. If you want to expand on a description, edit the existing answer for that abbreviation.

3. This is going to get long, so consistant formatting will help. For each answer (abbreviation), start with just the abbreviation within HTML "h1" and "/h1" tags on a line by itself.

4. Upvote answers for abbreviations you think would be acceptable to use in a post on this site without any expansion or explanation.

5. Downvote abbreviations (answers) you think should not be used "bare" on this site. This will be community-wiki, so nobody will loose reputation as a result. In this special case, you are voting on the universality of the abbreviation, not on the quality of the writeup. If you don't like the write up, fix it instead.

# INDEX

A - A(2) AC(7) ADC(15) ALU(3) AM(7) ASCII(12) ASIC(6) ASK(1) AWG(7)

B - BCD(5) BJT(16) BLDC(4) BNC(6) BPF(1) BW(3)

C - CAD(5) CAN(7) CC(1) CC-II(-1) CCCS(1) CCD(6) CMOS(16) CMRR(1) COG(0) CPLD(4) CPM(-1) CPU(7) CRO(-1)

D - DAC(15) DC(7) DEMUX(2) DFT(2) DIP(5) DLL(2) DMA(7) DRC(3) DSO(3) DSP(13) DTFT(0) DVD(-10) DVM/DMM(4)

E - ECL(4) EDA(6) EE(7) EEPROM(13) EMC(3) EMS(-7) EOS(0) EPROM(3) ESD(9)

F - F(2) FDNR(-3) FET(17) FFC(2) FFT(6) FIFO/LIFO(7) FM(7) FPGA(9) FSK(1) FSM(4)

G - GBW(5) GIC(-1) GND(16) GPIO(9) GPS(4)

H - H(2) HDTV(-11) HF(4) hFE(2) HPF(2) HVSP(-1) Hz(3)

I - i(-1) I/P(-7) I2S(1) IC(11) IF(4) IFT(1) IGBT(9) IGFET(0) ISP(4) I²C(13)

J - j(-1) JFET(10) JTAG(7)

K - KCL(6) KVL(6)

L - LCD(17) LED(19) LF(3) LPF(4) LSB, MSB(2) LUT(5) LVD(-1) LVDS(5) LVDT(0) LVS(-2)

M - MCU(6) MEMS(6) MIDI(4) MOSFET(17) MPU(-1) ms(2) MUX(6)

N - NEXT(-6) NPN(12) NTSC(0) NVM(0)

O - O/P(-7) OCXO(2) OLED(4) OP-AMP(8) OTA(3)

P - P-P(0) PAL (logic)(2) PAL (television)(0) PC(-1) PCB(17) PCBA(-5) PCM(4) PFM(-2) PIC(0) PID(9) PLL(9) PM(0) , duplicate(0) PNP(14) POR(3) PPM(-1) PSK(5) PUT(-1) PWM(24)

Q - QM(-6) QVGA(0)

R - RADAR(0) RAM(12) RF(5) RFID(6) RGB(4) RJ45(6) ROM(3) RTL (discrete logic)(2) RTL (Verilog)(2)

S - SAW(3) SCR(9) SD,SDHC(0) SDCC(-3) SMA(4) SMPS(9) SMT(5) SNR(5) SOC/SoC(5) SPI(13) SPICE(8) SRAM(6) SRPP(-2) STA(0)

T - TBH(-8) TCXO(2) THD(6) TRF(-1) TTL(10) TVS(4)

U - UART(12) UHF(4) UJT(0) UL(3) USART(4) USB(4)

V - V(2) VCA(1) VCC / VEE / VDD / VSS(14) VCCS(1) VCO(5) VCXO(3) VFD(3) VGA(-2) VHDL(7) VHF(5) VLSI(2) VNL,VFL(-1) VSWR(4)

W - W(2)

X - XO(1) XOR(3) XTAL(5)

Ω - Ω(0)

186 answers - Sun May 11 09:17:28 2014 (CET)

• IEEE's take on the subject May 12, 2014 at 19:41
• The links don’t seem to work. Not on iPhones anyway. May 19 at 23:06

## Hz

Hertz - one cycle per second

## kHz

Kilohertz - one thousand (103) cycles per second

## MHz

Megahertz - one million (106) cycles per second

## GHz

Gigahertz - one billion (109) cycles per second

## THz

Terahertz - one trillion (1012) cycles per second

• Should be only one abbreviation per answer. I think the units are useful but the metric prefixes are not necessary May 1, 2014 at 19:21
• @Gorloth I disagree. Firwt of all, I'm trying to show commonly used prefixes (e.g. millihertz is not used). Secondly, this allows just one entry in the index for H (Hertz), and a user can come to this entry to see all the variations. Otherwise you are going to glog the index with all the prefixes (which I think are important). Note this has gotten quite a few votes in its present form. May 1, 2014 at 20:15
• If you want commonly used values it seems like it would be sufficient to mention that in the description (Hz - hertz a unit of cycles per second, commonly used in kHz to Thz ranges) seems that metric prefixes are not really EE specific, maybe an edit to make the unit vs prefix distinction more clear, not sure how to best do that though May 2, 2014 at 0:57

# MIDI

Musical Instrument Digital Interface.

A standard for digital communication between electronic musical instruments, specifying both a protocol and hardware standards. MIDI data is usually transmitted over USB, or as a balanced serial data stream at 31.25kbps, using three conductors (+5V, signal, ground) and cables terminated in 5-pin 180° DIN plugs.

# UHF

Short for Ultra High Frequency (300 MHz ~ 3 GHz)

# HF

Short for "High Frequency".

# LPF

Short for "Low Pass Filter". Frequencies above the cut off frequency are attenuated.

• I have never heard this abbreviated like this, it would be nice to have someone weigh in as this is important in EE
– JFA
May 2, 2014 at 0:25

# IF

Intermediate Frequency. Commonly used in Superheterodyne Receivers, where the tuned radio frequency is mixed down to a fixed intermediate frequency, where in turn the signal is demodulated to the audio band. Eg. for PAL TV 38.9MHz.

## VCXO

Voltage-Controlled Crystal Oscillator. A crystal oscillator that can be "pulled" away from its nominal frequency by means of an analog control voltage.

# VSWR

Voltage Standing Wave Ratio. In RF technology when a transmission line is not properly terminated, the voltage along the line will vary.

# ALU

Arithmetic and Logic Unit. The arithmetic and logic brain in a microprocessor.

# EPROM

Erasable Programmable Read-Only Memory. Non-volatile memory which preserves it contents even without a power supply. It may be erased by applying ultraviolet light onto the die. EPROM memories have been mostly replaced by EEPROM memories.

# ROM

Data persists after power is removed.

# VFD

Variable-frequency drive, a type of adjustable-speed AC motor drive

OR

Vacuum fluorescent display, a high-intensity segment display technology

# UL

Underwriters Laboratories, a company that certifies the safety of a wide variety of electrical products

# SAW

Surface Acoustic Wave filter

# LF

Short for Low Frequency, often audio spectrum (0 - 20kHz)

# HPF

Short for "High Pass Filter". A High Pass filter attenuates frequencies below the cut off frequency.

# DFT

The Discrete Fourier Transform. A ordered sequence of numbers that represent the energy and phase of a discrete, periodic signal at some frequency (the frequency represented by the n-th term depends on how fast or 'close together' your input samples are; see other references).

For a discrete signal with period N, ${x_0,...,x_{N-1}}$, the DFT will be of length N, and the DFT at each $k$ from 1 to N is:

$$\tilde{X}(k)=\sum_{n=0}^{N-1}x(n)\cdot e^{-i2\pi k n/N}$$

Not to be confused with the DTFT!

# hFE

The large-signal current gain of a BJT transistor. Defined as IC/IB in the forward-active mode.

• I rather think, this parameter hFE is defined as the SMALL-SIGNAL forward current gain in common emitter configuration.
– LvW
May 10, 2014 at 9:11
• Can you provide a definition for Ic and Ib also in this summary? May 15, 2014 at 6:20

Amplitude Shift Keying.

Simple modulation method used for digital communications in which digital data is represented as variations in amplitude of carrier wave.

# FSK

Frequency Shift Keying.

Simple modulation method used for digital communications in which digital data is represented as variations in frequency of carrier wave.

# DSO

Digital Storage Oscilloscope.

Electronic testing/measuring instrument which can store and analyze the signal digitally. DSO use LCD display to show the signals.

# LSB, MSB

Least Significant Bit.

Most Significant Bit.

# VLSI

Very Large Scale Integration

# QFP

(A surface mount IC package)

# ARM

(Architecture for computer processors)

# RISC, CISC

RISC - Reduced Instruction set computing.

CISC - Complex Instruction set computing.

# EMI

Electromagnetic Interference. Undesirable and possibly problematic signal emitted by an electronic device. Emission of EMI is often restricted by organizations such as the United State's Federal Communications Commission.

# BW

"BW" is short for Bandwidth.

# OTA

Operational transconductance amplifier Similar to an opamp, but an output current instead of an output voltage. Effectively a voltage controlled current source.

# OCXO

Oven Controlled Crystal Oscillator. Although a crystal oscillator is already pretty stable by itself, it does however vary its frequency with temperature. By keeping the crystal in a small oven and warming it to a given and stable temperature, the output frequency is no longer influenced by external temperature variations.