To reduce power consumption of wireless terminals, we have developed ultra-low leakage regulator circuits that control the intermittent terminal operation with very small activity ratio. The regulator circuits supply about 100mA in the active mode and cut the leakage current to a nanoampere level in the standby mode. The operation of the ultralow-leakage regulator circuits with CMOS/SOI and bulk technologies is described. The leakage-current reduction mechanism in a proposed power switch with bulk technology is explained. Measurement shows that the power switch using reversely biased bulk transistors has a leakage current that is almost as small as that of conventional CMOS/SOI transistor switches.