Combined switch

Abstract

The invention discloses a combined switch. The combined switch comprises a junction field effect transistor and a diode. The junction field effect transistor comprises a gate electrode, a source electrode and a drain electrode; the diode comprises an anode and a cathode; the drain electrode of the junction field effect transistor is a first terminal of the combined switch; the source electrode ofthe junction field effect transistor is connected with the cathode of the diode; the gate electrode of the junction field effect transistor is connected with the anode of the diode; and the anode of the diode is a second terminal of the combined switch. Compared to a single diode, the combined switch disclosed by the invention has a higher reverse withstand voltage, and has zero reverse recovery characteristic and a lower forward turn-on voltage.

Description

technical field [0001] The present invention relates to the field of power supplies, and in particular to fast recovery switches. Background technique [0002] Fast recovery diode (FRD for short) is a semiconductor diode with good switching characteristics, short reverse recovery time or zero reverse recovery. It is mainly used in switching power supplies, PWM pulse width modulators, frequency converters and other electronic devices. In the circuit, it is used as a high-frequency rectifier diode, a freewheeling diode or a damping diode. The internal structure of the fast recovery diode is different from the ordinary PN junction diode. It belongs to the PIN junction diode, that is, the base region I is added between the P-type silicon material and the N-type silicon material to form a PIN silicon chip. Because the base region is very thin and the reverse recovery charge is very small, the reverse recovery time of the fast recovery diode is short, the forward voltage drop is ...

AI Technical Summary

Problems solved by technology

Schottky diodes have the advantages of high switching frequency and forward voltage drop, but their biggest disadvantages are their low reverse bias voltage and large reverse leakage current, such as Schottky diodes made of silicon and metal. The reverse bias rated withstand voltage is only up to 200V, there is no Si-based Schottky diode between 200 and 600V, the withstand voltage of SiC Schottky diode is only 600 / 650V / 1200V, and there is no SiC Schottky below 600V Diode, and the forward voltage drop is very high

The reverse leakage current value has a positive temperature characteristic, and it tends to increase rapidly as the temperature rises. It is necessary to pay attention to the hidden danger of thermal runaway in practical design.

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