# STATIC INDUCTION THYRISTOR

**URL:** <https://forumautomation.com/t/static-induction-thyristor/6456>\
**Category:** Electrical\
**Tags:** electrical\
**Created:** [May 27, 2019, 5:51pm UTC](https://forumautomation.com/t/static-induction-thyristor/6456 "2019-05-27T17:51:01Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ashlin](https://forumautomation.com/user_avatar/forumautomation.com/ashlin/32/3775_2.png) [@ashlin](https://forumautomation.com/u/ashlin)\
**Post date:** [May 27, 2019, 5:51pm UTC](https://forumautomation.com/t/static-induction-thyristor/6456/1 "2019-05-27T17:51:01Z")

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                    STATIC INDUCTION THYRISTOR 	

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This is a device which is capable of conducting large current with a low forward voltage and it can turn-off very fast, it is a self-controlled on-off device. A thyristor is a four-layered pnpn device which has three electrodes, the static induction thyristor it belongs to the static induction device family and it is a high power, high-frequency semiconductor device. It is a p+nn+ diode which has a buried P+ grid like gate structure

 ![image](https://cdn.forumautomation.com/original/2X/6/6f6782625db6c8c042c284d9d2256e226ca6b5a5.png)

**FEATURES**

• They are normally in on-state so gate electrodes will be negatively biased to hold off-state • At on-state it behaves similar to pin diodes • It has the power handling capability similar to the GTO • Faster switching speed than the GTO • It is a level-triggered and voltage driven device • In the si-thyristor the on-state voltage is low

 ![image](https://cdn.forumautomation.com/original/2X/c/cfb705b7a80b6faabdf871533905cc47dc3c727e.png)

The static induction thyristor had been developed in recent years normally it is an on-state device if the gate voltage is zero and the anode is positive it acts as a diode and the current will flow freely. When the PN junction is forward biased it will cause the injection of the hole to the N region and its conductivity would be modulated if the gate is reverse biased respect to cathode the depletion layer blocks the anode current and by this, the device gets off

\*\*WORKING \*\* **ON STATE**

The depletion region will be filled with carries when a positive voltage pulse is applied to the gates, and the device would be in on-state during the turn on-phase it will act as a pin diode and the turn on-process transition time is dominated by the rate of carrier injection time

![image](https://cdn.forumautomation.com/original/2X/0/0ac4ae4a6308bd0281d08fa411346ffefd78fb44.png)

**OFF STATE**

![image](https://cdn.forumautomation.com/original/2X/a/a5cac347b36f69e44fcf7872223d42941abb9b34.png)

Mostly it is in on-state gate electrodes need to be negatively biased, and the negative biased voltage to the gate forms a low conductive region around the gates and then the thyristor holds off-state

**ADVANTAGES** • It has high immunity for electromagnetic noise • It can handle rapid voltage or current change • It can obtain a higher breakdown voltage than FET • Low noise • High audio frequency power capability • It can be used in energy accelerator, current source inverter, and high-frequency power conversion