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Technical
Glossary - S
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| W,X,Y,Z | Spec.
Char., Number |
Saturated
The state of operation of a device or circuit
in which there is no increase in output for an
increase in input
SAW
Surface acoustic wave. Often short for surface
acoustic wave filter.
S-band
The frequency interval from 2 to 4 GHz.
Scalar
Of or pertaining to magnitude but not phase.
Schottky
A metal-semiconductor junction that has a nonlinear
voltage versus current characteristic.
Semiconductor
The elements or compounds whose conductivity falls
between that of conductors and insulators.
Sensitivity
The ratio of the response of a system or device
to the stimulus.
Series
Resistance
The real part of the complex impedance of a semiconductor
device. The resistance of the semiconductor package,
die attach and bond wire are typically included
in series resistance.
Series-Shunt
The circuit configuration including two components,
the first in series with the transmission line
and the second in shunt with the transmission
line.
Settling
Time
The time required for the device to attain 90
percent of the detected RF output referenced to
the 10 percent level.
Shunt
In parallel with.
Sideband
Suppression
In a mixer or modulator, the degree to which undesired
sidebands are reduced in amplitude.
Signal
Frequency
In a mixer or detector, this is the desired RF
or microwave frequency containing information
(modulation). This is the frequency that is to
be converted to a different (normally lower) frequency.
Signal
to Noise Ratio
The ratio of the magnitude of a desired signal
to that of noise.
Silicon
A semiconductor element, atomic number 14, in
group IVA of the periodic table of elements.
Single
Ended Mixer
The simplest form of mixer, which consists of
a single nonlinear impedance connected across
an unbalanced transmission line, to which RF and
LO signals are applied and from which the IF signal
is obtained.
Small
Signal
The magnitude of an AC signal which, when its
amplitude is halved or doubled, the characteristic
under measurement does not change.
Small
Signal Analysis
The consideration of the performance of a circuit
or device under small signal conditions
Smith
Chart
A mapping of the complex impedance plane onto
a polar plot. A Smith chart consists of circles
of constant resistance that intersect at Z = Â
and arcs of constant reactance that also intersect
at Z = Â. The horizontal diameter of the
Smith chart represents pure resistances from a
short (0 W) at one end to an open (Â W)
at the other end. The Smith chart was developed
by Philip H. Smith in the late 1930's.
SMR
Specialized mobile radio. A communications service
at 800 MHz and 900 MHz used to provide dispatch
messaging and cellular communications.
Snap
Time
(See "Transition Time")
SNR
(snr)
(See "signal to noise ratio")
Solid
State
In electronics, having or pertaining to circuits
that contain semiconductors. Note: In electro-optics,
used to refer to lasers and related devices made
of solid crystalline or amorphous materials other
than semiconductors.
SONET
Synchronous optical network, a North American
high speed baseband digital transport standard
for the transmission of data using fiber optics.
Source
The terminal at one end of the channel of a field
effect transistor by which electron or hole current
enters the channel. This terminal corresponds
to the emitter in a bipolar transistor.
SPICE
"Semiconductor Parameter In Circuit Emulator"
- a software package that emulates circuit performance
utilizing time domain analysis
Splitter
A component that divides the power from a signal
into two or more parts
Spurious
Undesired signals present at the output of a device
under test that are neither harmonics nor intermodulation
products, sometimes expressed as a percentage
of or decibels below the carrier.
Square-Law
Detection
Detection of an RF/microwave signal where the
magnitude of the detected video output voltage
is proportional to the square of the RF input
voltage
Square-Law
Detector
A detector circuit or device whose video output
voltage is proportional to the square of the RF
input voltage
Standing
Wave Ratio
The ratio of the maximum magnitude of a standing
wave to the minimum magnitude. SWR is indicative
of the degree to which there is a mismatch between
the characteristic impedance of the transmission
medium and its load. A standing wave ratio of
1:1 indicates a perfect match (all the power incident
on the load is absorbed by the load), while SWR
= Â indicates a complete mismatch (all the
power incident on the load is reflected by the
load).
Standing
Waves
The sum along a transmission medium of incident
and reflected waves, characterized by maxima and
minima along the medium.
Stripline
A multi-layer transmission line that consists
of two ground planes, separated by two layers
of dielectric material that sandwich between them
a thin center conductor that has a rectangular
cross section. The impedance of stripline is determined
by the thickness and dielectric constant of the
dielectric layers and the width of the center
conductor.
Super
Compact
A software package that analyzes and optimizes
RF/microwave circuits using frequency domain analysis.
Switch
An N-port device that directs energy from one
port to another or interrupts the flow of energy.
A switch can use mechanical, electromechanical
or electronic switching elements.
Switching
Time
The time required for the output of a switch to
attain 90 percent of its steady-state level referenced
to the 50 percent level of the command signal.
SWR
(See "Standing Wave Ratio")
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