Multi-GHz MVL Circuits Using Compound-Semiconductor Resonant-Tunneling Diodes

Compound semiconductor devices are commonly used in today’s wideband communications systems. In particular, they are indispensable to build the front-end stage, which is required to process high-frequency signals. Introduction of resonant-tunneling diodes (RTDs) to the front end would result in even better system performance. In the long term, such efforts are expected to pave the way for post-CMOS nano-electronics, where the basic principle is governed by the quantum mechanics. To develop RTD technology, we have to clarify characteristic features of RTDs, and to set a unique goal any other device technologies cannot reach near future. In our opinion, one possibility is an RTD-based A/D interface that relies on ultrahigh-speed switching combined with an ability to process multi-level signals. In this paper, we will briefly review this approach and discuss future challenges.