Parameter Selection of Fast-Switching Current Mirror for Active Gate Driver of High-Power Devices

As the switching frequency of power devices increases and the requirement of precision switching transient adjustment increases, the response speed of active gate driver (AGD) has become more demanding. However, the existing current source AGDs lack the ability to easily, quickly and accurately adjust the magnitude of the gate current. The theoretical analysis of the gate current switching process has not been studied. Therefore, in order to implement a controllable current source with fast switching speed, this article analyzes the switching process of the current mirror. The main device parameters affecting the current switching speed of the current source are revealed. The current switching speed of the current source is mainly related to the input capacitance of the MOSFET as branch switch, the equivalent capacitance of the PN junction of the BJT that constitutes the current mirror, and the damping coefficient of the output loop of the current source. For the design of current mirror in high-speed switching current source AGD, the device selection guidelines are proposed as well as circuit design. Finally, the dynamic switching effect of the proposed current source gate driver is verified by experiments.