Gate Turn-Off Thyristors
Content
Gate Turn-Off Thyristor
M.S.P.V.L Polytechnic College,
Pavoorchatram.
www.ustudy.in
Introduction
A Gate
Turn-Off
Thyristor
(GTO) is
a
special
type
of thyristor, a high-power semiconductor device.
GTOs, as opposed to normal thyristor, are fully controllable
switches which can be turned on and off by their third lead,
the GATE lead.
GTO thyristor can be fabricated with a reverse conducting
diode in the same package. These are known as RCGTO,
for Reverse Conducting GTO.
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Circuit diagram of GTO
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GTO Diagram and Symbol
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Reverse BIAS
GTO thyristor are available with or without reverse
blocking capability.
Reverse
blocking
capability
adds
to
the
forward
voltage drop because of the need to have a long, low
doped P1 region.
GTO thyristor capable of blocking reverse voltage are
known as Symmetrical GTO thyristor, abbreviated SGTO
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Functions of GTO
Gate turn-off thyristor (GTOs) are four-layer PNPN devices
that act as switches, rectifiers, and voltage regulators.
Like other thyristor, GTOs can be turned on by the
application of a positive gate signal (g > 0); however,
unlike other more conventional devices that can be turned
off only at a zero crossing of current, GTOs can be
turned off at any time by the application of a gate signal
equal to zero.
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Functions of GTO
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Functions of GTO
Performance specifications for gate turn-off thyristor (GTOs)
include
peak
repetitive
off-state
voltage,
peak
repetitive reverse voltage, peak cycle surge-on current,
maximum root mean square (RMS) current, and
holding current.
Peak
repetitive
off-state
voltage
(VDRM)
maximum instantaneous value of the off state.
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is
the
Cross section of GTO
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Operations of GTO
When a positive signal is applied, a GTO switches into
conduction state like the ordinary thyristor.
However in ordinary thyristor the current gains of NPN
and PNP transistors are very high so that gate sensitivity
for turn on is very high and on state voltage drop is low.
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Structure of GTO
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Operations of GTO
However in GTO, the current gain of PNP transistor is
low so that turn of its possible if significant current is drawn
from the gate.
When a negative gate signal is applied the excess
carriers are drawn from the base region of NPN transistor
and collector current of PNP is diverted to the gate.
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Operations of GTO
Thus the base drive of NPN transistor is
removed and this in turn removes the base drive
of PNP transistor and turnoff is achieved.
www.ustudy.in
The End
…… Thank You …….
www.ustudy.in
M.S.P.V.L Polytechnic College,
Pavoorchatram.
www.ustudy.in
Introduction
A Gate
Turn-Off
Thyristor
(GTO) is
a
special
type
of thyristor, a high-power semiconductor device.
GTOs, as opposed to normal thyristor, are fully controllable
switches which can be turned on and off by their third lead,
the GATE lead.
GTO thyristor can be fabricated with a reverse conducting
diode in the same package. These are known as RCGTO,
for Reverse Conducting GTO.
www.ustudy.in
Circuit diagram of GTO
www.ustudy.in
GTO Diagram and Symbol
www.ustudy.in
Reverse BIAS
GTO thyristor are available with or without reverse
blocking capability.
Reverse
blocking
capability
adds
to
the
forward
voltage drop because of the need to have a long, low
doped P1 region.
GTO thyristor capable of blocking reverse voltage are
known as Symmetrical GTO thyristor, abbreviated SGTO
www.ustudy.in
Functions of GTO
Gate turn-off thyristor (GTOs) are four-layer PNPN devices
that act as switches, rectifiers, and voltage regulators.
Like other thyristor, GTOs can be turned on by the
application of a positive gate signal (g > 0); however,
unlike other more conventional devices that can be turned
off only at a zero crossing of current, GTOs can be
turned off at any time by the application of a gate signal
equal to zero.
www.ustudy.in
Functions of GTO
www.ustudy.in
Functions of GTO
Performance specifications for gate turn-off thyristor (GTOs)
include
peak
repetitive
off-state
voltage,
peak
repetitive reverse voltage, peak cycle surge-on current,
maximum root mean square (RMS) current, and
holding current.
Peak
repetitive
off-state
voltage
(VDRM)
maximum instantaneous value of the off state.
www.ustudy.in
is
the
Cross section of GTO
www.ustudy.in
Operations of GTO
When a positive signal is applied, a GTO switches into
conduction state like the ordinary thyristor.
However in ordinary thyristor the current gains of NPN
and PNP transistors are very high so that gate sensitivity
for turn on is very high and on state voltage drop is low.
www.ustudy.in
Structure of GTO
www.ustudy.in
Operations of GTO
However in GTO, the current gain of PNP transistor is
low so that turn of its possible if significant current is drawn
from the gate.
When a negative gate signal is applied the excess
carriers are drawn from the base region of NPN transistor
and collector current of PNP is diverted to the gate.
www.ustudy.in
Operations of GTO
Thus the base drive of NPN transistor is
removed and this in turn removes the base drive
of PNP transistor and turnoff is achieved.
www.ustudy.in
The End
…… Thank You …….
www.ustudy.in
