Abbreviation for ampere, the unit of electrical current.
acceptor atoms
Trivalent atoms that accept free electrons from pentavalent atoms.
AC coupling
Circuit that passes an AC signal while blocking a DC voltage.
AC load line
A graph representing all possible combinations of AC output voltage and current for an amplifier.
active component
A component that changes the amplitude of a signal between input and output.
active filter
A filter that uses an amplifier in addition to reactive components to pass or reject selected frequencies.
active region
The region of BJT operation between saturation and cutoff used for linear amplification.
ADC
Abbreviation for Analog to Digital Converter.
Aliased signals
A signal (normally electrical) sampled below the Nyquist Rate (twice
the maximum frequency content of the signal) so that the frequency
content of signal is erroneously rearranged.
alpha
Ratio of collector current to emitter current in a bipolar junction
transistor (BJT). Greek letter alpha “α” is the symbol used.
amplifier
A circuit that increases the voltage, current, or power of a signal.
amplitude
Magnitude or size of a signal voltage or current.
analog
Information represented as continuously varying voltage or current
rather than in discrete levels as opposed to digital data varying
between two discrete levels.
anode
The positive electrode or terminal of a device. The “P” material of a diode.
Astable
A circuit that cannot remain in one state. That is it will periodically switch between states or oscillate.
attenuate
To reduce the amplitude of an action or signal. The opposite of amplification.
average value
A value of voltage or current where the area of the wave above the value equals the area of the wave below the value.
AWG
Abbreviation for Arbitrary Waveform Generator. Abbreviation for American Wire Gauge.
bandwidth
Width of the band of frequencies between the half power points.
barrier potential
The natural difference of potential that exists across a forward biased pn junction.
base
The region that lies between the emitter and collector of a bipolar junction transistor (BJT).
base biasing
A method of biasing a BJT in which the bias voltage is supplied to the base by means of a resistor.
beta
(β) The ratio of collector current to base current in a bipolar junction transistor (BJT).
bias
A DC voltage applied to a device to control its operation.
bipolar junction transistor
(BJT), A three terminal device in which emitter to collector current is controlled by base current.
bode plot
A graph of gain versus frequency.
branch current
The portion of total current flowing in one path of a parallel circuit.
breakdown voltage
Voltage at which the breakdown of a dielectric or insulator occurs.
bridge rectifier
A circuit using four diodes to provide full wave rectification. Converts an AC voltage to a pulsating DC voltage.
buffer
An amplifier used to isolate a load from a source.
bulk resistance
The natural resistance of a “P” type or “N” type semiconductor material.
BW
Abbreviation for bandwidth.
bypass capacitor
A capacitor used to provide an AC ground at some point in a circuit.
CAD
Abbreviation for “computer aided design”
calibration
To adjust the correct value of a reading by comparison to a standard.
CAN
Controller Area Network, a robust serial communication bus standard popular in automotive and industrial applications.
capacitance
The ability of a capacitor to store an electrical charge. The basic unit of capacitance is the Farad.
capacitor
An electronic component having capacitive reactance.
cascaded amplifier
An amplifier with two or more stages arranged in a series configuration.
cascode amplifier
A high frequency amplifier made up of a common-source or common-emitter
amplifier with a common-gate or common base amplifier in its
drain/collector network.
cathode
The negative terminal electrode of a device. The “N” material in a junction diode.
center tapped rectifier
Circuit that make use of a center tapped transformer and two diodes to provide full wave rectification.
center tapped transformer
A transformer with a connection at the electrical center of a winding.
charge
Quantity of electrical energy.
circuit
Interconnection of components to provide an electrical path between two or more components.
clamp
A diode circuit used to change the DC level of a waveform without distorting the waveform.
class A amplifier
A linear amplifier biased so the active device conducts through 360 degrees of the input waveform.
class B amplifier
An amplifier with two active devices. The active components are biased
so that each conducts for approximately 180 degrees of the input
waveform cycle.
class C amplifier
An amplifier in which the active device conducts for less than 180 degrees of the input waveform cycle.
clipper
A diode circuit used to eliminate part of a waveform above or below a limit.
closed circuit
Circuit having a complete path for current flow.
closed-loop gain
Gain of an amplifier when a feedback path is present.
collector
The semiconductor region in a bipolar junction transistor through which a flow of charge carriers leaves the base region.
collector characteristic curve
A graph of collector voltage over collector current for a given base current.
common base amplifier
A BJT circuit in which the base connection is common to both input and output.
common collector amplifier
A BJT circuit in which the collector connection is common to both input and output.
common drain amplifier
A FET circuit in which the drain connection is common to both input and output.
common emitter amplifier
A BJT circuit in which the emitter connection is common to both input and output.
common gate amplifier
A FET circuit in which the gate connection is common to both input and output.
common source amplifier
A FET circuit in which the source connection is common to both input and output.
common-mode rejection ratio
(CMRR) The ratio of op-amp differential gain to common-mode gain. A
measure of an op-amp's ability to reject common-mode signals such as
noise.
common-mode signals
Signals that appear simultaneously at two inputs of an operational
amplifier (op-amp). Common mode signals are always equal in amplitude
and phase.
CMOS - complimentary MOSFET logic.
CMOS logic dominates the digital industry because the power
requirements and component density are significantly better than other
technologies.
comparator
An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs.
complementary transistors
Two transistors, one NPN and one PNP having near identical
characteristics. N-channel and P-channel FETs can also be complementary.
constant current circuit
Circuit used to maintain constant current to a load having resistance that changes.
conventional current flow
Concept of current produced by the movement of positive charges towards the negative terminal of a source.
coulomb
Unit of electric charge. A negative coulomb charge consists of 6.24 × 1018 electrons.
coupling
To electronically connect two circuits so that signal will pass from one to the other.
current
Measured in amperes, it is the flow of electrons through a conductor. Also known as electron flow.
current amplifier
Amplifier to increase signal current.
current divider
Parallel network designed to divide the total current of a circuit.
current feedback
Feedback configuration where a portion of the output current is fed back to the amplifier input.
current mirror
Term used to describe the fact that DC current through the base circuit
of a class B amplifier is approximately equal to the DC collector
current.
cutoff
Condition when an active device is biased such that output current is near zero or beyond zero.
DAC
Abbreviation for “digital to analog converter.”
Darlington pair
An amplifier consisting of two bipolar junction transistors with their
collectors connected together and the emitter of one connected to the
base of the other. Circuit has an extremely high current gain and input
impedance.
DC
Abbreviation for “direct current”.
DC load line
A graph representing all possible combinations of voltage and current for a given load resistor in an amplifier.
DC offset
The change in input voltage required to produce a zero output voltage when no signal is applied to an amplifier.
DC power supply
Any source of DC power for electrical equipment.
decade
A frequency factor of ten.
decibel
(dB) a logarithmic representation of gain or loss.
degenerative feedback
Also called negative feedback. A portion of the output of an amplifier
is inverted and connected back to the input. This controls the gain of
the amplifier and reduces distortion and noise.
depletion layer or region
The area surrounding a PN junction that is depleted of carriers.
depletion mode
In a FET, an operating mode where reverse gate-source voltage is used
to deplete the channel of free carriers. This reduces the size of the
channel and increases its resistance.
depletion-mode MOSFET
A MOSFET designed to operate in either depletion mode or enhancement mode.
device
dielectric
Insulating material between two plates where an electrostatic field exists.
dielectric constant
Property of a material that determines how much electrostatic energy
can be stored per unit volume when unit voltage is applied.
dielectric strength
The maximum voltage an insulating material can withstand without breaking down.
differential amplifier
An amplifier in which the output is in proportion to the differences between voltages applied to its two inputs.
differentiator
A circuit in which the output voltage is in proportion to the rate of change of the input voltage. A high pass RC circuit.
diffusion
Tendency of conduction band electrons to wander across a PN junction to combine with valence band holes.
digital
Relating to devices or circuits that have outputs of only two discrete
levels. Examples: 0 or 1, high or low, on or off, true or false etc.
Digitizing oscilloscope
An oscilloscope that uses a high-speed analog-to-digital converter
(ADC) to measure signals and then displays them on a screen (CRT or LCD)
using standard computer graphics techniques.
diode
A two terminal device that conducts in only one direction.
direct coupling
Where the output of one amplifier stage is connected directly to the
input of a second amplifier or to a load. Also known as DC coupling
because DC signals are not blocked.
direct current (DC)
Current that flows in only one direction.
donor atoms
Pentavalent atoms that give up electrons to the conduction band in an N type semiconductor material.
doping
The process of adding impurity atoms to intrinsic (pure) silicon or
germanium to improve the conductivity of the semiconductor material.
electric charge
Electric energy stored on the surface of a material. Also known as a static charge.
electric field
A field or force that exists in the space between two different potentials or voltages. Also known as an electrostatic field.
electromotive force
(emf) Force that causes the motion of electrons due to potential difference between two points. (voltage)
electron
Smallest sub atomic particle of negative charge that orbits the nucleus of an atom.
electron flow
Electrical current produced by the movement of free electrons towards a positive terminal.
electrostatic
Related to static electric charge.
emitter
The semiconductor region from which charge carriers are injected into the base of a bipolar junction transistor.
emitter feedback
Coupling from the emitter output to the base input of a bipolar junction transistor.
emitter follower
A common collector amplifier. Has a high current gain, high input impedance and low output impedance.
engineering notation
A floating point system in which numbers are expressed as products
consisting of a number greater than one multiplied by an appropriate
power of ten that is some multiple of three.
enhancement-mode MOSFET
A field effect transistor in which there are no charge carriers in the channel when the gate source voltage is zero.
equivalent resistance
Total resistance of all the individual resistances in a circuit.
fall time
Time it takes the falling edge of a pulse to go from 90% of peak voltage to 10% of peak voltage.
farad
The basic unit of capacitance.
feedback
A portion of the output signal of an amplifier which is connected back to the input of the same amplifier.
feedback amplifier
An amplifier with an external signal path from its output back to its input.
field effect transistor (FET)
A voltage controlled transistor in which the source to drain conduction is controlled by gate to source voltage.
filter
Network consisting of capacitors, resistors and/or inductors used to pass certain frequencies and block others.
Flip Flop
A digital circuit that flips or toggles between two stable states
(bistable). The Flip Flop inputs decide which of the two states its
output will be.
forward bias
A PN junction bias which allows current to flow through the junction.
Forward bias decreases the resistance of the depletion layer.
free electrons
Electrons that are not in any orbit around a nucleus.
frequency-domain analysis
A method of representing a waveform by plotting its amplitude against frequency.
frequency response
Indication of how well a circuit responds to different frequencies applied to it.
frequency response curve
A graph of amplitude over frequency indicating a circuit response to different frequencies.
full wave rectifier
Rectifier that makes use of the full AC wave in both the positive and negative half cycles.
function generator
Signal generator that can produce sine, square, triangle and sawtooth output waveforms.
fundamental frequency
Lowest frequency in a complex waveform.
I2C
Inter integrated circuit bus, a short-distance serial communication bus
standard consisting of two signals (clock and data), popular for
talking between several integrated circuits on the same printed circuit
board.
IC
Abbreviation for “integrated circuit”
IC voltage regulator
Three terminal device used to hold the output voltage of a power supply constant over a wide range of load variations.
IGFET
Insulated gate field effect transistor. Another name for a “MOSFET.”
impedance
(Z) Measured in ohms it is the total opposition to the flow of current
offered by a circuit. Impedance consists of the vector sum of resistance
and reactance.
Interleave
A technique used in digitizing oscilloscopes whereby ADCs of different
analog channels are used together, normally resulting in higher sample
rate or more memory depth when you are using fewer channels.
internal resistance
Every source has some resistance in series with the output current.
When current is drawn from the source some power is lost due to the
voltage drop across the internal resistance. Usually called output
impedance or output resistance.
intrinsic material
A semiconductor material with electrical properties essentially
characteristic of ideal pure crystal. Essentially silicon or germanium
crystal with no measurable impurities.
inverting amplifier
An amplifier that has a 180° phase shift from input to output.
inverting input
In an operational amplifier (op amp) the input that is marked with a
minus sign. A signal applied at the inverting input will be given 180°
phase shift between input and output.
ion
An atom with fewer electrons in orbit than the number of protons in the
nucleus is a positive ion. An atom with a greater number of electrons
in orbit than the number of protons in the nucleus is a negative ion.
L-C tank circuit
A circuit consisting of inductance and capacitance, capable of storing
electricity over a band of frequencies continuously distributed about a
single frequency at which the circuit is said to be resonant or tuned.
light-emitting diode (LED)
A semiconductor diode that converts electric energy into
electromagnetic radiation at a visible and near infrared frequencies
when its pn junction is forward biased.
limiter
Circuit or device that prevents some portion of its input from reaching the output. See also clipper.
LIN
Local interconnect network, a short-distance serial communication standard that is often found in systems also containing the CAN bus. LIN is slower and less complex than the CAN bus.
linear
Relationship between input and output in which the output varies in direct proportion to the input.
linear scale
A scale in which the divisions are uniformly spaced.
line regulation
The ability of a voltage regulator to maintain a constant voltage when the regulator input voltage varies.
load
A source drives a load. Whatever component or piece of equipment is
connected to a source and draws current from a source is a load on that
source.
load current
Current drawn from a source by a load.
load impedance
Vector sum of reactance and resistance in a load.
loading effect
Large load impedance will draw a small load current and so loading of
the source is small. (light load). A small load impedance will draw a
large load current from the source. (heavy load).
load regulation
The ability of a voltage regulator to maintain a constant output voltage under varying load currents.
load resistance
majority carriers
The conduction band electrons in an n-type material and the valence
band holes in a p-type material. Produced by pentavalent impurities in
n-type material and trivalent impurities in p-type material.
metal oxide field effect transistor (MOSFET)
A field effect transistor in which the insulating layer between the gate electrode and the channel is a metal oxide layer.
mid-band gain
Gain of an amplifier operating within its bandwidth.
mid-point bias
An amplifier biased at the center of its DC load line.
mil
One thousandth of an inch (0.001 in.)
Miller's theorem
A theorem that allows you to represent a feedback capacitor as equivalent input and output shunt capacitors.
minority carriers
The conduction band holes in n-type material and valence band electrons
in p-type material. Most minority carriers are produced by temperature
rather than by doping with impurities.
Mixed-signal oscilloscopes (MSOs)
Digitizing oscilloscopes that have a larger number of channels than
usual for looking at both analog and digital signals. MSOs typically
have two or four analog channels and at least 8 bits of vertical
resolution. There are usually 16 digital channels but they typically
have only 1 bit of vertical resolution.
Monostable
A circuit that has one stable state. When perturbed, the circuit will
return to the stable state after some fixed amount of time.
MOSFET
Abbreviation for “metal oxide field effect transistor” also known as an
“insulated gate field effect transistor. A field effect transistor in
which the insulating layer between the gate electrode and the channel is
a metal oxide layer.
Multivibrator
A circuit used to implement a simple two-state system, which may be astable, monostable, or bistable.
n-type semiconductor
A semiconductor compound formed by doping an intrinsic semiconductor
with a pentavalent element. An n-type material contains an excess of
conduction band electrons.
negative
Terminal that has an excess of electrons.
negative charge
A charge that has more electrons than protons
negative feedback
A feedback signal 180° out of phase with an amplifier input signal.
Used to increase amplifier stability, bandwidth and input impedance.
Also reduces distortion.
negative ion
An atom having a greater number of electrons in orbit than there are protons in the nucleus.
negative resistance
A resistance such that when the current through it increases the voltage drop across the resistance decreases.
negative temperature coefficient
A term used to describe a component whose resistance or capacitance decreases when temperature increases.
node
Junction or branch point in a circuit.
noise
Unwanted electromagnetic radiation within an electrical or mechanical system.
non-inverting input
The terminal on an operational amplifier that is identified by a plus sign.
non-linear scale
A scale in which the divisions are not equally spaced, logarithmic.
Norton's theorem
Any network of voltage sources and resistors can be replaced by a single current source in parallel with a single resistor.
NPN transistor
A bipolar junction transistor in which a p-type base element is sandwiched between an n-type emitter and an n-type collector.
passive component
Component that does not amplify a signal. Resistors, capacitors and inductors are examples.
peak to peak
Difference between the maximum positive and maximum negative values of an AC waveform.
pentavalent element
Element whose atoms have five valence electrons. Used in doping
intrinsic silicon or germanium to produce n-type semiconductor material.
Most commonly used pentavalent materials are arsenic and phosphorus.
percent of regulation
The change in output voltage that occurs between no-load and full-load
in a DC voltage source. Dividing this change by the full-load value and
multiplying the result by 100 gives percent regulation.
percent of ripple
The ratio of the effective rms value of ripple voltage to the average value of the total voltage. Expressed as a percentage.
pinch-off region
A region on the characteristic curve of a FET in which the gate bias
causes the depletion region to extend completely across the channel.
PNP transistor
A bipolar junction transistor with an n-type base and p-type emitter and collector.
positive feedback
A feedback signal that is in phase with an amplifier input signal. Positive feedback is necessary for oscillation to occur.
potential difference
Voltage difference between two points which will cause current to flow in a closed circuit.
potentiometer
A variable resistor with three terminals. Mechanical turning of a shaft
can be used to produce variable resistance and potential. Example: A
volume control is usually a potentiometer.
power supply rejection ratio (PSRR)
A measure of an op-amps ability to maintain a constant output when the supply voltage varies.
protoboard
Board with provision for attaching components without solder. Also
called a breadboard. Primarily used for constructing experimental
circuits.
RC time constant
Product of resistance and capacitance in seconds.
recombination
Process by which a conduction band electron gives up energy (in the form of heat or light) and falls into a valence band hole.
rectification
Process that converts alternating current to direct current.
rectifier
Diode circuit that converts alternating current into pulsating direct current.
regenerative feedback
Positive feedback. Feedback from the output of an amplifier to the
input such that the feedback signal is in phase with the input signal.
Used to produce oscillation.
regulated power supply
Power supply that maintains a constant output voltage under changing load conditions.
regulator
Device or circuit that maintains a desired output under changing conditions.
resistance
Symbolized “R” and measured in ohms. Opposition to current flow and dissipation of energy in the form of heat.
resistor
Component made of material that opposes flow of current and therefore has some value of resistance.
reverse bias
Bias on a PN junction that allows only leakage current (minority
carriers) to flow. Positive polarity on the n-type material and negative
polarity to the p-type material.
reverse breakdown voltage
Amount of reverse bias that will cause a PN junction to break down and conduct in the reverse direction.
reverse current
Current through a diode when reverse biased. An extremely small current also referred to as leakage.
reverse saturation current
Reverse current through a diode caused by thermal activity. This
current is not affected by the amount of reverse bias on the component,
but does vary with temperature.
R-2R ladder
Network or circuit composed of a sequence of L networks connected in tandem. Circuit used in digital to analog converters.
saturation
Condition in which a further increase in one variable produces no
further increase in the resultant effect. In a bipolar junction
transistor, the condition when the emitter to collector voltage is less
than the emitter to base voltage. This condition puts forward bias on
the base to collector junction.
schematic diagram
Illustration of an electrical or electronic circuit with the components represented by their symbols.
scientific notation
Numbers entered as a number from one to ten multiplied by a power of ten. Example: 8765 = 8.765 × 103.
SDRAM
Synchronous dynamic random-access memory, the most popular form of
digital memory today. It differs from previous-generation DRAM in that
all signal timing is relative to one clock.
self biasing
Gate bias for a field effect transistor in which source current through
a resistor produces the voltage for gate to source bias.
semiconductor
An element which is neither a good conductor or a good insulator, but
rather lies somewhere between the two. Characterized by a valence shell
containing four electrons. Silicon, germanium and carbon are the
semiconductors most frequently used in electronics.
series circuit
Circuit in which the components are connected end to end so that current has only one path to follow through the circuit.
signal to noise ratio (SNR)
Ratio of the magnitude of the signal to the magnitude of noise usually expressed in decibels.
silicon
(Si) Non metallic element (atomic number 14) used in pure form as a semiconductor.
silicon dioxide
Glass like material used as the gate insulating material in a MOSFET.
silicon transistor
A bipolar junction transistor using silicon as the semi conducting material.
solid state
Pertaining to circuits where signals pass through solid semiconductor
material such as transistors and diodes as opposed to vacuum tubes where
signals pass through a vacuum.
source follower
FET amplifier in which signal is applied between gate and drain with
output taken between source and drain. Also called “common drain.”
source impedance
Impedance through which output current is taken from a source.
spectrum analyzer
Instrument used to display the frequency domain of a waveform plotting amplitude against frequency.
SPI
Serial Peripheral Interface, a very simple short-distance serial
communication bus standard consisting of either two (clock and data) or
three (clock, data and strobe) signals, popular for reading data from
microcontroller peripherals such as ADCs.
summing amplifier
An op-amp circuit whose output is proportional to the sum of its instantaneous voltages.
superposition theorem
Theorem designed to simplify networks containing two or more sources.
It states that in a network containing more than one source, the current
at any one point is equal to the algebraic sum of the currents produced
by each source acting separately.
valence shell
The outermost electron shell for a given atom. The number of electrons in this shell determines the conductivity of the atom.
varactor diode
PN junction diode with a high junction capacitance when reverse biased.
Most often used as a voltage controlled capacitor. The varactor is also
called: varicap, tuning diode and epicap.
variable capacitor
Capacitor whose capacitance can be change by varying the effective area of the plates or the distance between the plates.
variable resistor
Resistor whose resistance can be changed by turning a shaft. See also “potentiometer and rheostat.”
virtual ground
Point in a circuit that is always at approximately ground potential.
Often a ground for voltage, but not for current. The summing junction in
an op-amp circuit.
volt
Unit of potential difference or electromotive force. One volt is the
potential difference needed to produce one ampere of current through a
resistance of one ohm.
voltage
(V) Term used to designate electrical pressure or force that causes current to flow.
voltage amplifier
Amplifier designed to build up signal voltage. By design amplifiers can
have a large voltage gain or a large current gain or a large power
gain. Voltage amplifiers are designed to maximize voltage gain often at
the expense of current gain or power gain.
voltage divider
Fixed or variable series resistor network connected across a voltage to obtain a desired fraction of that voltage.
voltage divider biasing
Biasing method used with amplifiers in which two series resistors
connected across a source. The junction of the two biasing resistors
provides correct bias voltage for the amplifier.
voltage drop
Voltage or difference in potential developed across a component due to current flow.
voltage feedback
Feedback configuration where a portion of the output voltage is fed back to the input of an amplifier.
voltage follower
Operational amplifier circuit characterized by a high input impedance,
low output impedance and unity voltage gain. Used as a buffer between a
source and a low impedance load.
voltage gain
Also called voltage amplification. Ratio of amplifier output voltage to input voltage usually expressed in decibels.
voltage multiplier
Rectifier circuit using diodes and capacitors to produce a DC output
voltage that is some multiple of the peak value of AC input voltage.
Cost effective way of producing higher DC voltages. Voltage doublers and
voltage triplers are examples.
voltage regulator
Device or circuit that maintains constant output voltage (within
certain limits) in spite of changing line voltage and/or load current.
voltage source
Circuit or device that supplies voltage to a load.