# 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)

# PWM

Pulse Width Modulation. A method of controlling duty cycle by chopping as opposed to throttling.

## LED

Light Emitting Diode.

Blinking an LED is considered the "Hello world" of a circuit design, and it can be as simple as putting a series resistor or can get more complicated, involving PWM and multiplexing.

Tag:

# LCD

Liquid-Crystal Display, used to display characters or graphics

# CMOS

Complementary Metal Oxide Semiconductor.

or

# D/A

Digital-to-Analog Converter

or

# A/D

Analog-to-Digital Converter

# FET

Field Effect Transistor. There are various sub-types of this, like JFET (PN junction separates gate and body) and MOSFET (metal oxide insulated gate).

# PCB

Printed circuit board. A board made typically made out of a fiberglass reinforced epoxy (FR4), which has traces on at least one side and is used to mount electronic components.

Originally, PCBs had just through-hole components on one side, and thus the top was called the component side, and the bottom the solder side (where the traces were).

Now a PCB will often have traces and surface mount components on both sides, and may in addition have interior layers (in even numbers, so the total layers are 2, 4, 6, 8 etc.). These interior layers are used for additional traces or power planes.

# BJT

Bipolar Junction Transistor. See NPN and PNP.

The first transistors developed were of this type. After other types appeared (such as field effect transistors), the name BJT was chosen to differentiate these from the others.

# GND

Ground reference. The node in a circuit that is 0V by definition.

• But note that this can't always stand alone (and the definition is a little misleading when it suggests there is only one ground node/reference in any circuit). For example, electrical equipment may have "earth ground", "chassis ground", "analog ground", "digital ground", and one or more "isolated ground" nodes, often associated with external connections. – Ben Voigt May 11 '14 at 19:55
• Side note: it's not that the reference node is defined to be at a voltage of 0 V. Instead, it has a voltage of 0 V because it is measured with respect to itself. – Alejandro Nava Jan 8 at 10:41

# PNP

Positive-Negative-Positive. One of the two types of bipolar junction transistors (BJT). Here positive and negative refer to positively and negatively doped semiconductor regions.

# DSP

Digital Signal Processing/Processor

# VCC / VEE / VDD / VSS

VCC: Positive power rail voltage (usually in BJT technology)

VEE: Negative power rail voltage (usually in BJT technology)

VDD: Positive power rail voltage (usually in FET technology)

VSS: Negative power rail voltage (usually in FET technology)

What is the difference between $V_{CC}$, $V_{DD}$, $V_{EE}$, $V_{SS}$

• Although these are related, I believe they mentioned one term per definition. – JFA Apr 30 '14 at 20:01
• @JFA By all means, do feel free to add three answers but do cross-reference them. – jippie May 1 '14 at 19:13
• How about this? Vpp: programming/erase voltage (usually in PIC microcontrollers) – Kamil May 3 '14 at 17:25
• @Kamil Good one, but I think it deserves its own entry because it has little to do with power supply rails. – jippie May 3 '14 at 18:22

# SPI

Serial peripheral interface. A single master, multiple slave communication protocol. Clock rates can go into the 10's of MHz.

It comprises the following lines:

SCK - clock
MOSI - master out slave in (typically data from microcontroller to IC)
MISO - master in slave (typically data from IC back to microcontroller)
SS - slave select.  One SS is required for each IC on the same bus.


# EEPROM

Electrically Erasable Programmable Read-Only Memory, a type of non-volatile memory. Also sometimes referred to as E2PROM.

# I²C

(also I2C or IIC). Inter-integrated circuit. A single master, multiple slave communication protocol using a 2-wire serial bus (SCL - serial clock line and SDA - serial data line). Used to connect IC's on a PCB, and less often, IC's on different PCBs. Typical clock rates are 100 k and 400 k baud.

Unlike SPI, slave select lines are not required as each chip has a unique address.

• Sometimes this is also referred to as TWI (Two Wire Interface) – hassansin Apr 30 '14 at 19:28
• @hassansin I believe Atmel didn't want to pay the I²C license fee (to either Philips or NXP), so they came up with their own name. Not sure if the TWI spec is different in details or not. – jippie May 1 '14 at 19:27
• It is also referred to as IIC. – Lundin May 5 '14 at 11:21
• @Lundin Thanks, I added that. – tcrosley May 5 '14 at 12:16

# ASCII

American Standard Code for Information Interchange

# RAM

Random-access memory, a misnomer that usually refers to any volatile semiconductor memory. The term random access was originally used to differentiate memory technology that required sequential access to stored data (i.e. delay-line memory, rotating disks, magnetic and paper tape) from those memory technologies that would allow you to access any sequence of locations, in any order, without penalty. Strictly speaking, flash memory is a random-access memory but it is never categorized as RAM.

• It would be nice if you could elaborate on why it is a misnomer. – Jonathon Reinhart May 3 '14 at 6:25

# UART

Universal Asynchronous Receiver/Transmitter. A UART implements the common "serial" protocol, such as used by RS-232 and PC COM ports.

Data is sent on a single signal. Each word (typically a 8-bit byte) is sent by a start bit, followed by the data bits, followed by a stop bit. The bit timing must be agreed on by both ends ahead of time. The receiver uses the leading edge of the start bit as the time reference for the remaining bits in that word. The stop bit is at the line idle level, and guarantees that the there will be a transition at the leading edge of the next start bit.

# IC

Integrated circuit, a semicondutor device incorporating several circuit elements

# JFET

Junction field effect transistor. A type of FET.

This is the original FET. After the development of the MOSFET, the Junction designation was added to distinguish it from other types.

# NPN

Negative-Positive-Negative, indicating the type of doping of each region. One of the two types of bipolar junction transistors (BJT).

• it stands for n-doped, p-doped, n-doped. or n-type, p-type, n-type. – scordova88 Apr 30 '14 at 22:08

# ESD

Electrostatic discharge. "Static electricity." Particularly dangerous to CMOS parts. Sometimes used to refer to the process of dealing with static discharge susceptibility in design.

# SCR

Silicon Controlled Rectifier.

SCRs are unidirectional devices triggered only by currents going into the gate.

• Once triggered, they continue to conduct until the load current is removed. They are also called "thyristors". – gbarry Jan 16 '16 at 7:18

# GPIO

General Purpose Input / Output

This is usually used to refer to a pin of a microcontroller that can be either input or output under firmware control. It can also refer to a externally available signal of a circuit board or whole device that is intended to produce or receive a digital signal, depending on configuration or other usage.

# SMPS

Switch-mode power supply (or switch-mode power supply unit) - can be generally applied to any or combinations of the following: -

• Buck converter
• Boost converter
• Fly-back converter
• SEPIC converter (single-ended primary-inductor converter)
• [list not exhaustive]

# PLL

Phase-Locked Loop. Used for frequency synthesis and FM demodulation.

# TTL

Transistor-Transistor Logic

# FPGA

Field-Programmable Gate Array A type of programmable logic device that uses LUTs (Look Up Table) to implement complex logic.