6 Comparison of the Two Methods

Both the methods are capable of providing current-boosted drive output. However, the saturated MOSFET-based drive can achieve much higher drive currents due to the lower impedance offered by the saturated MOSFETs. The BJT drive is relatively higher impedance, as they operate in active region and hence will not be able to reach the drive current levels achieved by the other method while using devices of comparable size. Also, the availability of high-current BJT devices is far less compared to high-current MOSFETs. While driving similar devices, the BJT-based driver will dissipate more power in it than the MOSFET based driver, due to the relatively higher impedance of the BJT. The relatively cooler operating temperature increases the reliability of the MOSFET-based driver .

The major advantage with the BJT-based driver is the simplicity of the circuit. It has fewer components and a much simpler power scheme. It also allows easy extension of the features built inside the driver IC like DESAT protection, Miller clamp , and so forth. For the MOSFET-based driver, these functions should be built externally, if needed. So the overall size of the gate driver will increase due to external DESAT protection and clamping circuitry. However, the MOSFET-based driver gives more flexibility for isolation, as it depends on the transformer and digital isolator only. There are more devices to choose from in case of specific isolation requirements.