Multi-threshold Threshold Logic Circuit Design Using Resonant Tunneling Devices

This Letter presents a novel and extremely compact circuit topology able to implement a generalized threshold logic function with two thresholds. The circuit consists of resonant tunnelling diodes (RTDs) and heterostructure field effect transistors (HFETs). Introduction: Resonant tunneling devices are nowadays considered the most mature type of quantum-effect devices. They are already operating at room temperature and the existence of a III-V large scale integration process allows us to explore novel circuit architectures [1]. Resonant tunneling diodes (RTDs) exhibit a negative differential resistance (NDR) region in their current-voltage characteristics which can be exploited to significantly increase the functionality implemented by a single gate in comparison to MOS and bipolar technologies. In particular, a number of Threshold Gates (TGs) based on RTDs monolitically integrated with three-terminal devices which implement complex logic functions have been fabricated and have demonstrated high speed and robust operation [1].