Super low power 8-bit CPU with pass-transistor logic

A very low power 8-bit CPU core has been designed based on an original pass-transistor logic family, the SPL (single-rail pass-transistor logic) and SPHL (single-rail pass-transistor and holders logic). The instruction set and external timings are compatible with the Zilog Z80. The average supply current is 740 /spl mu/A at 3 V with a 10 MHz-clock, equivalent to 26% of that of the commercial CMOS Z80 CPU cores using the same design rules.