If the length is very short (less than 0.05 mi-
crons for GaAs), then quantum effects play a
role in device operation.
gate turn off device
(1) any power semi-
conductor switching device which can turned
off with a signal to its gate.
(2) a thyristor capable of gate-turn-off op-
eration.
gate turnoff thyristor
a thyristor that can
be turned off with a negative gate current
while conducting current in the forward di-
rection.
gate width
the width in microns of that
portion of a FET channel associated with a
single gate, as measured in the direction or-
thogonal to channel current flow, that can be
pinched off by application of the proper con-
trol bias. A single FET structure may include
many subcells placed in parallel with each
other, resulting in a much higher gate periph-
ery for more power (i.e., 4 individual FETs,
each with a gate of 100 microns, may be par-
alleled together to form a 4
× 100 micron
FET with a gate periphery of 400 microns).
gate-to-drain breakdown voltage
the
breakdown voltage of the reverse biased gate-
to-drain junction of an FET. Usually it is
specified at a predetermined value of current
per millimeter of gate periphery.
gate-to-drain capacitance
the capaci-
tance between the gate and drain terminals
of a FET. It is formed primarily by the ca-
pacitance of the FET’s physical interconnect
structure (extrinsic fixed capacitance) and by
the depleted region capacitance (intrinsic ca-
pacitance), which is a function of voltage and
temperature.
gate-to-source breakdown voltage
the
breakdown voltage of the reverse-biased
gate-to-source junction of an FET. Usually it
is specified at a predetermined value of cur-
rent per millimeter of gate periphery.
gate-to-source capacitance
the capaci-
tance between the gate and source terminals
of a FET. It is formed primarily by the ca-
pacitance of the FET’s physical interconnect
structure (extrinsic fixed capacitance) and by
the depleted region capacitance (intrinsic ca-
pacitance), which is a function of voltage and
temperature.
gate-to-source voltage
the potential dif-
ference between the FET gate and source
terminals, this voltage controls the channel
from saturation to pinchoff. This voltage is
normally negative for an n-channel FET, and
positive for a p-channel FET. However, ei-
ther of these devices can be operated in a
slightly enhanced mode, allowing low-level
excursions of the opposite polarity.
gateway
See
router
.
Gauss’ law
fundamental law of electro-
magnetic field that states that the total elec-
tric/magnetic flux through a closed surface
is equal to the total electric/magnetic charge
enclosed.
Gauss’ theorem
See
divergence theorem
.
Gaussian aperture
aperture in which the
transmission profile is a Gaussian function of
radius.
Gaussian approximation
an approxima-
tion used in statistics where the distribution of
a sum of random variables is approximated
by the Gaussian distribution. Such an ap-
proximation is based on the central limit the-
orem of probability.
Gaussian beam
electromagnetic beam
solution of the paraxial wave equation in
which the field has spherical phase fronts and
is a Gaussian function of distance from the
beam axis.
Gaussian distribution
a probability den-
sity function characterized by a mean
µ and
c
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