PHASE-MODE CIRCUITS FOR HIGH-PERFORMANCE LOGIC

We present two types of ICF (INHIBIT Controlled by Fluxon) gates as th e basic circuits of the phase-mode logic family, and fabricate an adde r circuit. The experimental result demonstrates that the carry operati on followed up to 99 GHz input pulses. The performance of Josephson de vices is improved by the use of junctions with high current density (J (c)). We may use the high-J(c) junctions without external resistive sh unt in the phase-mode logic circuits because of reduction of the junct ion hysteresis. One of the ways to overcome the large area occupancy F or geometric inductance is to utilize the effective inductance of a Jo sephson junction itself. We investigate a circuit construction with hi gh-J(c) inductor junctions, intrinsically overdumped junctions and jun ction-type resistors for the compactness of circuit integration, and d iscuss various aspects of the circuit construction.