AI-1
APPENDIX I
GLOSSARY
AMPERE-TURN—The magnetomotive force developed by one ampere of current flowing through a
coil of one turn.
AMPLIFICATION—The process of enlarging a signal in amplitude (as of voltage or current).
AMPLIFIER—A device that enables an input signal to control an output signal. The output signal will
have some (or all) of the characteristics of the input signal but will generally be larger than the input
signal in terms of voltage, current, or power.
AMPLITUDE—The size of a signal. Generally used to describe voltage, current, or power.
AUDIO AMPLIFIER—An amplifier designed to amplify frequencies between 15 hertz (15 Hz) and 20
kilohertz (20 kHz).
BANDWIDTH—The difference between the highest usable frequency of a device (upper frequency
limit) and the lowest usable frequency of the device (lower frequency limit)—measured at the half-
power points.
BYPASS CAPACITOR—A capacitor used to transfer unwanted signals out of a circuit; e.g., coupling
an unwanted signal to ground. Also called a DECOUPLING CAPACITOR.
COMBINATION PEAKING—A technique in which a combination of peaking coils in series and
parallel (shunt) with the output signal path is used to improve high-frequency response.
COMPENSATION—The process of overcoming the problems associated with frequencies in an
amplifier.
COUPLING—The process of transferring energy from one point in a circuit to another point or from one
circuit to another.
COUPLING CAPACITOR—A capacitor used to couple signals.
DECOUPLING CAPACITOR—A capacitor used to transfer unwanted signals out of a circuit; e.g.,
coupling an unwanted signal to ground. Also called a BYPASS CAPACITOR.
DEGENERATIVE FEEDBACK—Feedback in which the feedback signal is out of phase with the input
signal, also called NEGATIVE FEEDBACK.
DIFFERENTIAL AMPLIFIER—An amplifier with an output which is determined by the difference
between two input signals and which can provide up to two output signals.
DISTORTION—Any unwanted change between an input signal and an output signal.
DRIVER—An electronic circuit that supplies the input to another circuit.
FEEDBACK—The process of sending part of an output signal of an amplifier back to the input of the
amplifier.
