Gate driver, a part of the electronics driver family, is known as a powerful amplifier. It is a powerful amplifier that is built to take low power input from a controller IC and then for a power device convert it into the required high current gate drive. In recent times, the design and performance of gate driver circuitry are becoming increasingly critical as power electronics requirements grow.
In power electronics, the metal oxide semiconductor field-effect transistor and the insulated gate bipolar transistor are two of the most common and efficient semiconductor devices for switching power supplies of medium to high power.
The electrically separated control terminal for each device is the gate of a MOSFET or IGBT. In order to operate a MOSFET/IGBT, a voltage must be provided to the gate that is relative to the device’s source/emitter. The gate terminal must be made positive with respect to the source/emitter in order to push these switching devices into conduction.
The parasitic capacitances between the three terminals, i.e., gate-to-source (Cgs), gate-to-drain (Cgd), and drain-to-source (Cds), are usually nonlinear and a function of bias voltage, affect the power device switching behavior.
When the gate capacitor is charged, the power device is turned on and current can flow between its drain and source terminals, however, when it is discharged, the device is turned off and a significant voltage is blocked across the drain and source terminals.
Power Electronics Gate Drivers
The gate of a power switch can never be operated by the output of a logic IC in high-power applications (PWM controller). Because these logic outputs have limited current capacities, charging the gate capacitance would take an inordinate amount of time, most certainly longer than a switching period. As a result, separate drivers must be employed to apply a voltage and drive current to the power device’s gate.
Gate Drivers comes in the following shapes and sizes:
- Low-Side Drivers – These are used to power ground-connected switches (low side switches).
- High-Side-Low-Side Drivers – Used to power two switches in a bridge configuration
- Isolation of Gate Drivers
For both functional and safety reasons, gate drive circuits for power inverters and converters frequently require electrical isolation. To avoid shock dangers, regulatory and safety certification bodies require isolation. It also safeguards low-voltage electronics from damage caused by high-power circuit faults and human mistakes on the control side.
Many power device applications (such as converters that require high power density and efficiency) necessitate the use of an isolated gate driving circuit. Because low side drivers cannot be utilized directly to drive the upper power device especially in power converters such as half-bridge, full-bridge, buck, two-switch forward, and active clamp forward, there are high and low switches.