The technical challenges of developing very-high-power-density power supplies operating of switching frequencies in the vicinity of 10 MHz are considered. Primary applications are in the computer, telecommunications, and automotive industries. It is shown that a successful development requires simultaneous considerations of topologies, materials, devices, control, electromagnetic interference, manufacturing, and packaging. Some results of work being done at MIT are presented, including a new integrated power MOSFET/driver, high-field frequency magnetic material characterizations, and high-frequency synchronous rectifiers. The design and performance of a 50-W 3.5-MHz converter is described.>