Figure 8-1 shows the circuit used to measure most switching parameters. The top device in this circuit is used to re-circulate the inductor current and functions in third-quadrant mode only. Only the LMG3422R030 must be used as the top device as it does not have the ideal-diode mode feature. Do not use the LMG3425R030 for the top device. If the top device has the ideal-diode mode feature, it will automatically turn on the GaN FET when the inductor current is re-circulating and cause a shoot-through current event when the bottom device turns on. The bottom device is the active device that turns on to increase the inductor current to the desired test current. The bottom device is then turned off and on to create switching waveforms at a specific inductor current. Both the drain current (at the source) and the drain-source voltage is measured. Figure 8-2 shows the specific timing measurement. TI recommends to use the half-bridge as double pulse tester. Excessive third-quadrant operation can overheat the top device.