A reduced-swing internal bus scheme is proposed for achieving ultralow-power LSI's. The proposed data-dependent logic swing bus (DDL bus) uses charge sharing between bus wires and an additional bus wire to reduce its voltage swing. With this technique, the power dissipation of the proposed bus is reduced to 1/16 that of a conventional bus when used for a 16-b-wide bus. In addition, a dual-reference sense-amplifying receiver (DRSA receiver) has been developed to convert a reduced-swing bus signal to a CMOS-level signal without loss of noise margin or speed. Experimental circuits fabricated using 0.5-µm CMOS process verify the low-power operation of the proposed bus at an operating frequency of 40 MHz with a supply voltage of 3.3 V.

Coplanar silicon-coupled bridge type Josephson junctions with recessed niobium electrode structure were fabricated with a new planarization process and Josephson current was observed for the device with an electrode spacing of 50 nm. This device structure has potential to a three-terminal supercouductive device controlled by an insulated gate.

Random modulation refers to the changing of the MOSFET threshold voltage cell by cell. This paper claims it is essential in sub-2-V CMOS design because it reduces the sub-threshold leakage current even in the active and sleep modes as well as in the stand-by mode. We found that a gradated modulation scheme, which gradually changes the ratio of low- Vth cells according to the path-delay, is the best approach. To achieve the minimal leakage current, the way of determining the optimum pair of threshold voltages is also described. Experimental results for microprocessor show that gradated modulation reduces sub-threshold leakage current by 75% to 90% compared to conventional single-low-threshold voltage design without degrading the performance of the circuits.