What is the difference between thyristor​, Field-effect transistor and triode?

What is the difference between thyristor, Field-effect transistor and triode?

Field-effect transistor VS triode

1. The source electrode s, grid electrode g and drain electrode d of the Field-effect transistor correspond to the emitter e, base electrode b and collector c of the triode respectively, and their functions are similar

2. Field-effect transistor is a voltage controlled current device, whose iD is controlled by vGS. Its amplification coefficient gm is generally small, so Field-effect transistor has poor amplification ability; A transistor is a current controlled current device controlled by iB (or iE) to control iC

3. The grid of Field-effect transistor takes almost no current (ig ± 10); When the triode works, the base always draws a certain current, so the input resistance of the Field-effect transistor is higher than that of the triode

4. Field-effect transistor only has many carriers to conduct electricity; The triode has two kinds of carriers, the multi carrier and the minority carrier, which participate in the conduction. The minority carrier concentration is greatly affected by temperature, radiation and other factors, so the Field-effect transistor has better temperature stability and strong radiation resistance than the transistor. The Field-effect transistor should be selected when the environmental conditions (temperature, etc.) change greatly

5. When the source water is connected with the substrate, the source and drain of Field-effect transistor can be used interchangeably, and the characteristics change little; When the collector and emitter of a transistor are interchanged, their characteristics differ greatly, and the b value will decrease significantly

6. The noise figure of Field-effect transistor is very small, so Field-effect transistor shall be used in the input stage of low-noise amplifier circuit and the circuit requiring high signal to noise ratio

7. Both Field-effect transistor and triode can form various amplification circuits and open circuit circuits, but because the former has simple manufacturing process, low power consumption, good thermal stability, wide operating power supply voltage range and other advantages, it is widely used in large-scale and Very Large Scale Integration

thyristor VS (triode/Field-effect transistor)

thyristor is a special type of diode, abbreviated as a thyristor rectifier element. It is a high-power semiconductor device with a four layer structure of three PN junctions, generally composed of two thyristors connected in reverse. Its function is not only rectification, but also as a contactless switch to quickly connect or cut off circuits, achieving the inversion of direct current into alternating current, converting alternating current of one frequency into alternating current of another frequency, and so on.

Thethyristor diode can be simulated using two transistors with different polarities (P-N-P and N-P-N). When the gate of the thyristor is suspended, both BG1 and BG2 are in the cut-off state. At this time, there is basically no current flowing through the load resistor RL in the circuit. When a positive pulse voltage is input to the gate, BG2 is turned on, causing the base potential of BG1 to decrease. Therefore, BG1 begins to turn on, and BG1's turn on further increases the base potential of BG2, causing the base potential of BG1 to decrease, After this positive feedback process, BG1 and BG2 enter a saturated channel on state. The circuit quickly transitions from a cut-off state to a channel on state, and even if the gate does not trigger a pulse, the circuit will remain in the channel on state due to the positive feedback effect. If reverse voltage is applied to both the anode and cathode at this time, the circuit will quickly shut down due to both BG1 and BG2 being in a reverse bias state, In addition, if the resistance value of the load resistor RL is increased to reduce the circuit current, the base current of BG1 and BG2 will also be reduced. When it decreases to a certain value, due to the positive feedback effect of the circuit, the circuit will quickly flip from the on state to the off state, and we call this current the maintenance current. In practical applications, we can short circuit the anode and cathode of the thyristor through a switch to achieve the turn-off of the thyristor.