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Micro-electro-mechanical relays with multiple gate electrodes (i.e., multiple input voltage signals), operated with a tunable body bias voltage, are investigated for more compact and energy-efficient implementation of digital logic circuits. Specifically, a relay design with three gate electrodes of equal area is demonstrated to be capable of performing different digital logic functions for the same input operating voltage (${V} _{\textbf {DD}}$), by adjusting the body bias voltage. Since the lower limit for ${V} _{\textbf {DD}}$ is equal to the switching hysteresis voltage (${V} _{\textbf {H}}$), the magnitude of ${V} _{\textbf {H}}$ is investigated for different combinations of transitioning input voltage signals. It is found that ${V} _{\textbf {H}}$ is larger for fewer transitioning input voltage signals, i.e., reduced effective actuation area of the switching input voltage signal. This can set a practical upper limit for the number of independent gates in a single relay. [ABSTRACT FROM AUTHOR]

Body-biased micro-electro-mechanical (MEM) relays previously have been demonstrated to be a promising alternative to transistors for ultra-low voltage digital logic applications. A basic requirement for reliable relay-based circuit operation is suitably low and stable relay ON-state resistance ($R_{\mathbf {ON}}$). In this work, the effect of body biasing on $\text{R}_{\mathbf {ON}}$ is investigated for relays of different contact designs. It is found that a single direct contact design not only provides for the smallest hysteresis voltage but also the smallest $R_{\mathbf {ON}}$ , making it the most suitable for low voltage applications. Body-biased operation is found to degrade $R_{\mathbf {ON}}$ stability over many ON/OFF switching cycles, however, due to a reduction in contact velocity. [2020-0297] [ABSTRACT FROM AUTHOR]

The energy efficiency of a CMOS digital logic circuit is fundamentally limited by the nonideal switching behavior of transistors, specifically their nonzero off-state current and finite subthreshold slope. In contrast, mechanical switches (relays) can achieve zero off-state current and perfectly abrupt switching characteristics; therefore, they have attracted growing interest for ultralow-power computing applications. A challenge for electro-mechanical relay technology is to reduce the hysteresis voltage, because this sets the minimum operating voltage of the relays. Herein, we report a surface-micromachinedelectrostatically actuated relaywith <70-mV hysteresis voltage, achieved by designing it to have relatively large structural stiffness and to operate in nonpull-inmode. A relay-based inverter circuit is demonstrated to operate reliably with a switching voltage below 100 mV, representing a significant milestone toward ultralow-power mechanical computing. [ABSTRACT FROM AUTHOR]