Multiple-valued logic circuits using resonant tunneling diodes

The intent of this poster demonstration is to explain how resonant tunneling diodes (RTDs) can be utilized to design multiple-valued logic (MVL) circuits in a very compact and efficient manner, where the non-linear fold-back characteristic of RTDs provides unique advantages in the realization of specific functions that are central to the design of MVL circuits. At the University of Michigan, a comprehensive effort is being made to demonstrate through simulation, validation and fabrication that RTDs and associated tunneling devices such as BSRTTs, RHETs, RTBTs, etc. can be employed to realize ultra-high-speed and ultra-high-density digital circuits. Here, we show four different types of multi-valued logic circuits consisting of RTDs in conjunction with HBT and CMOS devices: multivalued gate arrays, multivalued 4-step counter, multivalued multiplexer, and multivalued signed-digit adder. These designs have been simulated using NDR-SPICE, a circuit simulator that has been developed at the University of Michigan to handle quantum electronic devices, and their at-speed performance has been accurately estimated by using a suite of CAD tools, also developed at the University of Michigan. The circuits have been built at the bread-board level by using discrete components, and their functionalities were verified. We have then transferred the technical knowhow to Lockheed Martin for monolithic fabrication of the first three MVL circuits.