A power converter can include: a first power terminal and a second power terminal; a first upper series-stacked high electron mobility transistor (HEMT) module connected to the first power terminal and a first intermediate terminal; a first lower series-stacked HEMT module connected to the second power terminal and the first intermediate terminal; a first inductor connected to the first intermediate terminal and a third power terminal; and a fourth power terminal connected to the second power terminal. Each of the first upper and first lower series-stacked HEMT modules can have a first plurality of HEMTs and a first series-switch-driver connected to each gate of the first plurality of HEMTs.