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Technical
Glossary - C
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| B | C | D
| E | F
| G | H
| I | J,K
| L | M
| N | O
| P | Q
| R | S
| T | U,V
| W,X,Y,Z | Spec.
Char., Number |
Capacitance
The property of conductors and dielectrics that
permits storing electricity when a potential differences
exists between conductors. The value of capacitance
is expressed as the ratio of the electric charge
to the voltage between the conductors. The unit
of capacitance is the Farad (F).
Capacitive
Decoupling
The establishment of AC ground or a low impedance
point for AC signals at a point in a circuit as
a result of the presence of capacitance between
that point and ground.
Capacitive
Reactance
The opposition to alternating current flow presented
by a capacitance. The symbol for capacitive reactance
is XC. The unit is the ohm. The formula for capacitive
reactance is
XC = 1/(2ðfC),
where:
f is the frequency of the alternating current
signal, and
C is the capacitance.
Capacitor
A two terminal device consisting of two conductors
separated by a dielectric material. A capacitor
will block direct current flow but will allow
alternating current flow as determined by its
capacitive reactance.
Carrier
Suppression
The degree to which the carrier signal is reduced
in amplitude in a modulator or mixer. Carrier
suppression is usually expressed in dB.
Cascade
A tandem arrangement of two or more components
in which the output of one component is connected
to the input of the next component.
Cathode
(1) In a semiconductor diode, the terminal to
which positive charge carriers flow internally
and into which negative charge carriers enter
from the external circuit. (2) In electron tubes,
the electrode from which electrons are emitted
into the inter-electrode space.
CATV
Community antenna television (cable television)
CDMA
Code Division Multiple Access. A digital transmission
technique based on direct sequence spread spectrum.
CDPD
Cellular Digital Packet Data.
Cellular
A wireless phone system that uses a grid of 'cells',
each managed by a base station. Often refers to
such systems that operate in or around the 800
- 1,000 MHz band.
centi
A prefix that indicates a factor 10-2, abbreviated
as "c.."
Ceramic
An insulating material having properties similar
to those of glass, notably hermeticity. In the
RF/microwave industry, the most frequently used
ceramic materials are alumina (Al2O3), aluminum
nitride (Al3N4), and beryllia (BeO).
Channel
(1) A band of frequencies. (2) A single path for
transmitting electric signals. (3) The conducting
layer in an FET between the source and drain.
Channel
(1) A frequency interval or frequency band assigned
for communications. (2) A single path for the
transmission of electric signals, where the term
"path" may refer to separate frequencies
or time slots. (3) The conducting layer in an
FET between the source and drain.
Characteristic
Impedance
The ratio of voltage and current at every point
along a transmission line on which there are no
standing waves.
Chip
A piece of semiconductor substrate (usually rectangular)
on which active and/or passive circuit elements
have been fabricated.
Circuit
A system of conductors and components through
which electrical current flows.
Circulator
A multiport device that propagates signals from
one port to the adjacent port with low loss in
one direction and with high loss in the opposite
direction.
Coaxial
Cable
A cylindrical transmission line structure consisting
of a central conductor surrounded by a dielectric,
which is in turn surrounded by a second, cylindrical
conductor (called the shield or outer conductor).
The cylinders subtended by center conductor, dielectric
and outer conductor all share the same axis.
Collector
Current
The current that flows through the collector of
a bipolar transistor.
Collector
The region of a bipolar transistor into which
current flows from the base of the transistor
under the influence of reverse bias across the
two regions.
Component
A device or physical element in an electronic
system that performs an electrical or electronic
function.
Compression
(1) The reduction in expected output power from
a device or network that results from saturation
of the device as a result of increased input power
to the device. (2) The process of eliminating
redundancy in a stream of data to represent the
data in a more compact manner without destroying
the meaning or information contained in the data.
Conductance
The reciprocal of resistance. The unit of conductance
is the siemens, abbreviated as "S."
The unit of conductance was the "mho,"
which was once shown as an upside down capital
omega.
Conductor
A device or material through which current flows
easily
Continuous
Wave
The state of operation in which there is no interruption
of the presence of a signal. The succeeding cycles
of a continuous wave are identical.
Conversion
Loss
The reduction of signal power as a result of the
conversion from the signal frequency to the IF
frequency by a down converting mixer. Since this
is defined as a loss, a reduction in power is
considered as a positive conversion loss.
LC = (IF output power)/(signal input power).
Conversion loss can also be expressed in dB:
L (dB) = -10 log (PIF/ PRF).
When referring to a mixer diode, conversion loss
is the loss in an optimum single-ended mixer carefully
designed to minimize losses in the RF and LO coupling
networks. Conversion loss normally includes power
transferred to the image frequency that is resistively
terminated.
Corner
Frequency
The frequency at which linear extrapolations of
two contiguous sections of a device's or component's
transfer function drop by 3 decibels.
Coupler
A class of multiport components that directs the
majority of an incident signal to the output port
and the remainder of the signal to other ports.
Coupling
Factor
The ratio of the input power of a coupler to the
output power from the coupled port. Coupling factor
is typically expressed in decibels (dB).
CW
(See "continuous waves").
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