Ultra-Low Power Data Converters with BEOL NEM Relays

With the fundamental limitation on transistor scaling and energy efficiency, Nano-electromechanical (NEM) relays have emerged as a promising alternative solution for ultralow power integrated circuits due to their zero leakage and steep subthreshold properties. In this paper, we explore the implementation of the I/O interface circuits, namely the analog-to-digital converter (ADC) and the digital-to-analog converter (DAC), with back-end-of-line (BEOL) NEM relays. The proposed design for the ADC comparators eliminates the need for reference generation by utilizing a bank of NEM relays with different pullin voltages. The decoder and encoder of both data converters are optimized by using a minimum number of devices and exclusive, non-leaking paths for each input and output code. As a result, while the sampling rate and operation frequency of the relay-based converters are inherently lower than CMOS counterparts due to mechanical nature of operation, the proposed data converters can achieve at least one order of magnitude lower energy consumption, which makes them appealing alternatives for ultra-low power VLSI and Internet of Things (IoT) applications.