Applications of resonant-tunneling diodes to high-speed digital ICs

Ultrahigh-speed circuit applications of resonant-tunneling diodes (RTDs) have been developed. The key points are the utilization of the edge-triggered and latching properties arising from the negative differential resistance of the RTD, and the combination of RTDs and high electron mobility transistors (HEMTs). High-speed and low power operation of various flip-flop (FF) circuits monolithically integrating InP-based RTDs and HEMTs have been demonstrated at room temperature, including a delayed flip-flop operation at 35 Gbit/s. By extending the concept of electronic-input circuits to the optical-input circuit, an ultrahigh-speed optoelectronic circuit integrating RTDs and a photodiode has been developed. Using this optoelectronic circuit, we have succeeded in demultiplexing a 80 Gbit/s optical signal into a 40 Gbit/s electrical signal. These results show the potentiality of RTD-based circuits for ultrahigh-speed communications and signal processing circuits.