A Sub-0.5 V Differential ED-CMOS/SOI Circuit with Over-1-GHz Operation

This paper describes a speed-oriented ullralow-voltage and low-power SOI circuit technique based on a differential enhancementand depletion-mode (ED)-MOS circuit. Combining an ED-MOS circuit block for critical paths and a multi-V th CMOS circuit block for noncritical path, that is, the so-called differential ED-CMOS/SOI circuit, makes it possible to achieve low-power and ultrahigh-speed operation of over 1 GHz at a supply voltage of less than 0.5 V. As two applications of the differential ED-CMOS/SOI circuit, a multi-stage frequency divider that uses the ED-MOS circuit in a first-stage frequency divider and a pipelined adder with a CMOS pipeline register are described in detail. To verify the effectiveness of the ED-CMOS/SOI circuit scheme, we fabricated a 1/8 frequency divider and a 32-bit binary look-ahead carry (BLC) adder using the 0.25-μm MTCMOS/SOI process. The frequency divider operates down to 0.3 V with a maximum operating frequency of 3.6GHz while suppressing power dissipation to 0.3 mW. The 32-bit adder operates at a frequency of I GHz at 0.5 V.