Abbreviations and Acronyms
New acronyms appear in the literature each year. As time goes by, many of these acronyms fall into disuse. In a few cases, meanings may differ depending on the industry where they originate. It is possible for one abbreviation to have several meanings. When this happens, the reader must rely on the intent of the author. As an example, pH can mean hydrogen ion concentration or picohenry. The correct meaning should be obvious in context.
Authors often coin an acronym in an article when a word group is repeated many times. Sometimes, an acronym is used in one company, but it is not used by the industry. These acronyms will not appear in this list.
The following list includes the common abbreviations used in circuit board design, mathematics, electrical engineering, and physics. Fortunately, acronyms that survive rarely conflict with scientific or engineering abbreviations.
Abbreviations that do not conform to present day usage or good practice are not listed. Here are a few of the problem areas. The first letter in many engineering measurement terms is an “m”. In an abbreviation, “m” could stand for milli, micro, or mega. It is good practice to use capital M for mega, small m for milli, and the Greek μ for micro. The letter m can also stand for meter, milliwatt, and mile. In the abbreviation dBm, the m means milliwatt. If m means meter, it can usually be inferred by context.
In an old copy of “The Radio Engineers Handbook” by Terman, the term mc is used as the abbreviation for megacycle. Today, the accepted abbreviation is MHz and it is read megahertz. We have come a long way in standardizing abbreviations.
Proper names used in engineering abbreviations require a capital letter. As an example, the A in mA stands for Andre Marie Ampere the French physicist. When the word ampere is used in a sentence, it is not capitalized. “ma” is not found in this list.
This list contains most of the common abbreviations used in this book and in circuit board design. It is not a complete list. It shows how extensively we use abbreviations and acronyms. It is hard to remember them all. If you do not find an abbreviation, the internet will usually provide some help.
A | Ampere, the unit of current |
ac | Alternating current. Usually a sine wave of voltage or current |
A/D | Analog-to-digital |
am | Amplitude modulation |
amp | Ampere (not recommended) |
ANSI | American National Standards Institute |
ASCII | American standard code for information interchange |
ASIC | Applications specific integrated circuit |
ASSP | Application-specific standard product |
ASTTL | Advanced Shottkey transistor–transistor logic |
ATE | Automatic test equipment |
B | Magnetic induction field, measured in teslas |
BGA | Ball grid array |
BH | B and H fields in a magnetic material. Hysteresis curves |
BOM | Bill of materials |
b/s | Bits per second |
BST | Barium-strontium-titanate (ceramic) |
BTL | Bipolar transistor logic |
BTU | British thermal unit |
BW | Bandwidth |
c | Velocity of light |
C | Capacitor, capacitance |
C | Coulomb. The unit of charge |
C12 | A mutual capacitance |
CAD | Computer-aided design |
CAM | Computer-aided manufacturing |
cc | Cubic centimeter |
CFFT | Complex fast Fourier transform |
CISPER A and B | EMI standards that are set by the EU |
cm | Centimeter |
CMOS | Complimentary metal oxide semiconductor |
cmr | Common-mode rejection |
cmrr | Common-mode rejection ratio (analog) |
cos | Cosine |
cot | Cotangent |
CPC | Computer power center |
cps | Cycles per second. Not in common use |
CRT | Cathode ray tube |
CSA | Canadian Standards Association |
csc | Cosecant |
Cu | Copper |
D | Displacement field |
D/A | Digital to analog |
dB | Decibel. 10 log P1/P2 or 20 log V1/V2. P2 or V2 are reference levels. |
dBA | Decibel-amperes |
dBm | Decibel-milliwatts |
dBV | Decibel-volts |
dBμV | Decibel-microvolts |
dc | Direct current. A steady value describing volts, current, or field strength. |
Df | Dissipation factor |
DFF | D flip flop |
DFM | Design for manufacturability |
DFT | 1. Design for test 2. Discrete Fourier transform |
DIP | Dual inline package |
Dk | Dielectric constant |
DRAM | Dynamic random access memory |
DTL | Decoupling transmission line |
e | 2.71828. Base of natural logarithms |
E | Electric field strength. Basic unit is volts per meter |
E | Energy in joules |
ECAD | Electronic computer-aided design |
ECL | Emitter-coupled logic |
EDA | Electronic design automation |
EE | Electrical engineer |
EIA | Electronics Industry Association |
EM | Electromagnetic |
EMC | Electromagnetic compatibility |
emf | Electromotive force, voltage |
emi | Electromagnetic interference |
ENIG | Electroless nickel/immersion gold |
EPROM | Electrically programmable read only memory |
ESD | Electrostatic discharge |
ESL | Equivalent series inductance |
ESR | Equivalent series resistance |
EU | European Union |
f | Frequency |
F | Farad, the unit of capacitance |
FB | Feedback |
FCC | Federal Communications Commission |
FET | Field effect transistor |
FFT | Fast Fourier transforms |
FIFO | First in first out |
FILO | First in last out |
fm | Frequency modulation |
FP | Field programmable |
FPGA | Field programmable gate array |
FR-4 | Flame resistant class 4 circuit board laminate. Glass epoxy |
FTTL | Fast TTL |
g | Gram |
G | Gauss, 10−4 teslas |
GaAs | Gallium arsenide |
Gb/s | Gigabits per second |
GHz | Gigahertz, 109 Hz |
GND | Ground |
GTL | Gunning transistor logic |
H | 1. Magnetic field strength, Basic unit is amperes per meter 2. henry, unit of inductance |
HASL | Hot air solder leveling |
HDI | High density interconnect |
HF | High frequency |
HSTL | High speed transceiver logic |
Hz | hertz (frequency). 1 Hz = 1 cycle per second |
IBIS | I/O buffer information specification |
i | 1. Varying current. 2. Square root of −1 |
IC | Integrated circuit |
id | Inside diameter |
IEEE | Institute of Electrical and Electronic Engineers |
I/O | Input/output |
IP | Intellectual property |
IPC | Institute of Printed Circuits |
IR | Infrared |
ISDN | Integrated Services Digital Network |
J | Joule |
JEDEC | Joint Electronics Device Engineering Council |
JFET | Junction FET |
k | Kilo, 103 |
kb/s | Kilobytes per second |
KB | Keyboard |
kg | Kilogram |
kHz | Kilohertz, 103 Hz |
km | Kilometer, 103 m |
kV | Kilovolt, 103 V |
kW | Kilowatt, 103 W |
kΩ | Kiloohms, 103 ohm |
L | Inductor, inductance |
L12 | Mutual inductance |
LAN | Local area network |
LED | Light emitting diode |
LCC | Leaded chip carrier |
LICA | Low inductance capacitor array |
ln | Natural logarithm (base e) |
log | Logarithm (base 10) |
LRC | Inductor/resistor/capacitor |
LVCMOS | Low voltage CMOS |
LVDS | Low voltage differential signaling |
m | 1. Meter 2. Milli |
M | Mega, 106 (M mean 1000 in Roman numerals but not in engineering) |
mA | Milliampere, 10−3 A |
Mb/s | Mega bits per second |
MCAD | Mechanical computer-aided design |
MCM | Multi chip module |
mH | Millihenry |
MHz | Megahertz, 106 Hz |
mil | 0.001 inches |
Mil | Military |
Mil Std | Military standard |
mJ | Millijoule |
mm | Millimeter |
mmf | Magneto motive force |
MOS | Metal oxide semiconductor |
MOSFET | Metal oxide semiconductor field effect transistor |
ms or msec | Millisecond, 10−3 s |
mV | Millivolt, 10−3 V |
mW | Milliwatt, 10−3 W |
mΩ | Milliohm, 10−3 ohm |
MΩ | Megaohm, 106 ohm |
N | Newton |
n | Nano, 10−9 |
nA | Nanoampere, 10−9 A |
NEC | National Electrical Code |
NEMA | National Electrical Manufacturing Association |
nF | Nanofarad, 1000 pF, 0.001 μF, 10−9 F |
nH | Nanohenry |
nm | Nanometer |
npn | Transistor made from a p-doped semiconductor layer between two n layers |
ns | Nanosecond, 10−9 s |
OC | Optical carrier |
od | Outside diameter |
OEM | Original equipment manufacturer |
p | Pico, 10−12 |
PC, pc | 1. Printed circuit 2. Personal computer |
PCA | Printed circuit assembly |
PCB | Printed circuit board |
PCI | Personal computer interface |
PE | Professional engineer |
PECL | Positive ECL |
pf | Power factor |
pF | Picofarad, 10−12 F |
pH | Picohenry, 10−12 H |
PLL | Phase-locked loop |
pn | Junction of positive and negative doped semiconductor, diode |
pnp | Transistor, n-doped semiconductor between two p layers |
ps | Picosecond, 10−12 s |
PTFE | Polytetrafluoroethylene (dielectric) |
PWB | Printed wiring board |
PWR | Power |
Q | A measure of losses in resonance. Low loss equals high Q |
QA | Quality assurance |
QFP | Quad flat pack |
R | Resistor, resistance |
RAM | Random access memory |
RC | Resistor/capacitor |
rf | Radio frequency |
rfi | Radio frequency interference, general interference |
rms | Root mean square |
RoHM | Reduction of hazardous material (lead free) |
ROM | Read only memory |
rpm | Revolutions per minute |
rps | Revolutions per second |
RTI | Referred to input |
RTO | Referred to output |
s | Second |
SCR | Silicon controlled rectifier |
sec | 1. Second (not recommended) 2. Secant |
Si | Silicon |
SI | Signal integrity |
SIP | Single inline package |
SMD | Surface mounted device |
SMT | Surface mount transistor |
SPICE | Special program for integrated circuit emulation |
SRAM | Static random access memory |
SWR | Standing wave ratio |
t | Time |
T | 1. tesla, the unit of magnetic induction 2. Temperature |
tan | Tangent |
TBD | To be determined |
TC | Temperature coefficient |
TDR | Time domain reflectometer |
TE | Transverse electric (wave) |
TEL | 1. Transitional electrical length. The distance a wave travels in a rise time 2. Telephone |
TELCO | Telephone company |
TT | Resin transition temperature in laminates |
TIA | Telecommunications Industry Association |
TL | Transmission line |
TM | Transverse magnetic (wave) |
TQFP | Thin quad flat pack |
TTL | Transistor–transistor logic |
TV | Television |
UHF | Ultrahigh frequency |
UL | Underwriters Laboratories |
USB | Universal serial bus |
UTP | Unshielded twisted pair |
v | Varying voltage |
V | Volt |
V | Volume usually in meters cubed |
VA | Volt-amperes |
VAR | Volt amperes reactive |
Vcc | Positive voltage on a circuit board |
VCR | Voltage controlled rectifier |
Vdd | Positive voltage on a circuit board |
VME | Type of bus and hardware protocol |
VOHmax | Highest loaded voltage for a logic 1 of a driver |
VOHmin | Lowest loaded voltage for a logic 1 of a driver |
VOLmax | Highest loaded voltage for a logic 0 of a driver |
Vss | The ground or most negative voltage on a circuit board |
VSW | Voltage standing wave |
W | Watt |
W | Work |
wan | Wide area network |
X | Reactance in ohms |
Y | Admittance in mhos |
Z | Impedance in ohms |
β | Current gain for a transistor |
ε R | Relative dielectric constant, permittivity |
θ | Angle, phase, or phase angle |
λ | Wavelength |
μR | Relative permeability |
μ | Micro, 10−6 |
μA | Microampere, 10−6 A |
μF | Microfarad, 10−6 F |
μH | Microhenry |
μm | Micrometer, 10−6 m |
μs | Microsecond, 10−6 s |
μV | Microvolt, 10−6 V |
π | 3.14159 |
ρ | 1. Resistivity 2. Reflection coefficient |
σ | Conductivity |
τ | Transmission coefficient |
τr | Rise or fall time |
ϕ | Angle, phase, or phase angle |
ω | Radian frequency, 2πf |
Ω | ohm |
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