Page 319 - Electrical Engineering Dictionary

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

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