Research Projects

A Micromechanical Power Amplifier

Clark Nguyen

Defense Advanced Research Projects Agency

This project aims to demonstrate methods for amplifying signals with higher efficiency compared to transistor circuits using mechanical means. Transistor-based switched-mode power amplifiers have been proposed for improving the power-added efficiency(PAE) of typical linear power amplifiers. However, due to transistor non-idealities, e.g. leakage current, large parasitic capacitance, low breakdown voltage, etc, switched-mode power amplifiers using transistor switches cannot achieve the 100% efficiencies predicted by theory under ideal conditions. To circumvent transistor deficiencies, this project aims to utilize a new on-chip micromechanical switch, dubbed the “resoswitch”, which harnesses the high stiffness and high Q of mechanical resonance to effect good reliability and low switch input capacitance compared to that of a transistor switch, while also offering smaller series resistance. One major advantage of the resoswitch-based power amplifier over its transistor-based counterpart is the high voltage handling ability of the former, which then allows it to dispense with the output transformer, greatly reducing loss and allowing the circuit to achieve a much higher efficiency.

Figure 1: Figure 1: Circuit topologies of a conventional Class E amplifier using a transistor switch device, and one simplified rendition of the proposed Class E amplifier utilizing the vibrating mechanical resonator switch described herein (left); the schematic and SEM photo of the mechanical resonator switch indicating the transistor-analogous operations (right).

[1]

Yang Lin, Wei-Chang Li, Zeying Ren and Clark T.-C. Nguyen, "The Micromechanical Resonant Switch("Resoswitch")," Solid State Sensor, Actuator and Microsystems Workshop, Hilton Head, SC 2008

[2]

Yang Lin,; Wei-Chang Li,; Zeying Ren,; Nguyen, Clark T.-C., "A resonance dynamical approach to faster, more reliable micromechanical switches," Frequency Control Symposium, 2008 IEEE International, pp.640-645, 19-21 May 2008