Superjunction Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) as a Pulsed Constant-Current Load

In this effort, I designed and tested a gate drive to pulse partly on a silicon Si superjunction high-voltage power metal-oxide-semiconductor field effect transistor MOSFET as a constant-current load. This load is for use in a reverse-recovery measurement circuit and is pulsed partly on during, up to 1 ms, and from just before the device-under-test DUT MOSFET is conducting until just after the DUT is off. Some measurements want a constant ID the load MOSFET had its initial partly on VGS fine-tuned to select ID up to 20 A, which is constant with load VDS from a small value up to much of its rating. During the pulse, our control circuit measured ID and maintained it somewhat constant, with feedback reducing the VGS. ID through the loads VDS generated heat that reduced VGSth, thus needing our feedback. This initial investigation found oscillations that made analog control not ideal to keep the load MOSFET ID constant.