Design method of switching circuit for depletion device with rcd network

Abstract

The invention discloses a design method for a switch circuit of a depletion device with an RCD network. The switch circuit includes an N-channel depletion-type GaN switch device Q1, an N-channel enhanced switch device Q2, a resistor R1, Capacitor C1 and diode D1, the source of the depletion-mode GaN switching device Q1 is connected to the drain of the enhancement-mode switching device Q2 and the cathode of the diode D1, the gate of the depletion-mode GaN switching device Q1 is connected to the resistor One end of R1, the negative pole of the polarized capacitor C1 and the anode of the diode D1 are connected. The method includes the steps of: 1. Selecting a polar capacitor C1 with appropriate parameters and resistors R1, R2 and R3; R1, polarized capacitor C1, diode D1, resistors R2 and R3. The invention enhances the rapidity, reliability and practicability of turning off the depletion switch device.

Description

technical field [0001] The invention belongs to the technical field of switch circuits, and in particular relates to a design method of a switch circuit with an RCD network depletion device. Background technique [0002] In recent years, semiconductor gallium nitride switching devices have attracted extensive attention in the industry due to their excellent performance characteristics, such as fast switching speed, low on-resistance, and high withstand voltage. However, limited by the current manufacturing process, GaN switching devices can only be made into depletion-mode switching devices. The characteristic of the depletion switching device is that it can be turned on when the voltage between the gate and the source is close to zero, and it can only be turned off when the negative voltage between the gate and the source reaches a certain value, which brings difficulties to the control , if it is directly applied to the existing switching power supply or switching power c...

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Problems solved by technology

[0003] The Chinese patent with application number 201020116685.3 discloses a combination switch circuit of enhanced-depletion devices that can be turned off reliably, which better solves the problem of on-off control of depletion-type switching devices, and can reliably turn off the depletion GaN switching device; however, the depletion-mode switching device Q1 and the N-channel enhancement-mode switching device Q2 cannot be turned off at the same time, and the depletion-mode switching device Q1 depends on the N-channel enhancement-mode switching device Q2, so that The depletion-type switching device Q1 cannot be turned off quickly; moreover, since the turn-off speed of the combined switching device depends on the magnitude of the current flowing through the depletion-type switching device, and the magnitude of the current depends on the load of the switching power supply, in When the load is light, there will be a small current flowing through the depletion switching device when it is turned off, so that the charging current to the equivalent capacitance between the drain and source of the enhancement switching device is small, resulting in depletion The turn-off speed of the switching device is slow, which makes it difficult to take advantage of the fast switching speed of the GaN device.

In order to solve this problem, the Chinese patent application number 201020130489.1 discloses a driving circuit that can quickly turn off the depletion-mode switching device, which not only inherits the reliability of the drive, but also better solves the problem of depletion-mode GaN The fast turn-off problem of the device, however, the driving circuit needs an external power supply VCC, and three switching devices are required, which increases the complexity of the circuit and increases the cost of the circuit, and the switching speed is slow, and the depletion-type switching device The conduction of Q3 depends on the P-channel enhanced switching device Q1, and the turn-off of the depletion-type switching device Q3 depends on the N-channel enhanced switching device Q2. The switching device Q1 is turned on at the same time, and the depletion switching device Q3 and the N-channel enhancement switching device Q2 cannot be turned off at the same time.

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