High-speed resonant tunneling flip-flop circuit employing a monostable-bistable transition logic element (MOBILE) with an SCFL-type output buffer

A resonant tunneling flip-flop circuit was fabricated based on a monostable-bistable transition logic element (MOBILE). In this work, an SCFL-type output buffer and depletion-mode HEMTs were employed differently than in previous studies. A practical output voltage level close to the SCFL interface was first demonstrated with a MOBILE circuit operating at a high bit rate of up to 20 Gb/s. This indicates that the MOBILE has sufficient current drivability. Another advantage of employing an SCFL output buffer is also described. This is, that D-HEMTs fabricated with precise gate-recess technology using an InP etch stopper can be used for MOBILEs. Good uniformity of the device parameters of the HEMTs and the RTDs were obtained simultaneously with this implementation. These results indicate the promise of using the MOBILE circuit in practical applications.