ADVANTAGES AND WORKING OF THE STATIC INDUCTION THYRISTOR

                    STATIC INDUCTION THYRISTOR 	

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

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

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

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OFF STATE

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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

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