Increased Logic Functionality of Clocked Series-Connected RTDS

The augmentation of transistor technologies with resonant tunnelling diodes (RTDs) has demonstrated improved circuit performance. The negative differential resistance exhibited by these devices can be exploited to increase the functionality implemented by a single gate in comparison to transistor-only technologies. Complex threshold gates (TGs) are efficiently realized by resorting to the operation principle of the clocked series connection of a pair of RTDs (MOBILE). This paper focuses the implementation of logic blocks using RTDs and transistors which further increase the functionality of previously reported topologies. Multithreshold-threshold gates (MTTGs) is the logic concept underlying the proposed realizations. The MOBILE principle is extended to three or more RTDs in series which allows us to implement MTTGs. Novel and extremely compact realizations of programmable gates using the MTTG topology are presented. A number of logic blocks useful for digital design are shown and their operation is verified through simulation with extensively validated models for actual devices