The document provides an overview of Gate Turn-Off Thyristors (GTO), detailing their construction, principles of operation, and applications. GTOs are high-power semiconductor devices similar to standard thyristors but with enhanced turn-off capabilities. Key applications include AC drives, DC choppers, and power supply stabilization.

1. BASUCS OF
ELECTRCALS
Prepared bu Atheena Pandian
GATE TURN-OFF THYRISTOR
(GTO)

2. Topic Outline Presentation Guide
What is GTO?
Symbol
Construction
Principle of Working
V-I Charateristics
Applixations
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2.
3.
4.
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6.

3. Basics of Electricals
What is GTO?
A gate turn-off thyristor (GTO) is a special
type of thyristor, which is a high-
power semiconductor device. It was invented
by General Electric

4. Simplified cross
section of a GTO
thyristor

5. Electronic
sy
mbol
of
GT
O

6. Equivalentcircuit
ofaGTOthyristor

7. Sy
mbol co
mparision
Basics of Electricals

9. Construction
Consider the above structure of GTO, which
is almost similar to the thyristor.
It is also a four layer, three junction P-N-P-N
device like a standard thyristor.
In this, the n+ layer at the cathode end is
highly doped to obtain high emitter
efficiency.
This result the breakdown voltage of the
junction J3 is low which is typically in the
range of 20 to 40 volts.
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10. Construction
The doping level of the p type gate is highly graded because the doping level
should be low to maintain high emitter efficiency, whereas for having a good turn
OFF properties, doping of this region should be high.
In addition, gate and cathodes should be highly interdigited with various
geometric forms to optimize the current turn off capability.

11. Construction
The junction between the P+ anode and N base is called anode junction.
A heavily doped P+ anode region is required to obtain the higher efficiency anode
junction so that a good turn ON properties is achieved.
However, the turn OFF capabilities are affected with such GTOs.

12. Principle of Operation

13. How does GTO
work?
During the turn ON, GTO is similar to
thyristor in its operates.So the first
quadrant characteristics are similar to the
thyristor.
When the anode is made positive with
respect to cathode, the device operates in
forward blocking mode.
By the application of positive gate signal
triggers the GTO into conduction state.

14. V-I
Characteristics
GTO

15. Gate Turn-Off Thyristor
Applications
AC drives
DC drives or DC choppers
AC stabilizing power supplies
DC circuit breakers
Induction heating
And other low power applications
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It is used as a main control device in choppers and
inverters. Some of these applications are

16. Thank You