A high-precision, wide-bandwidth micromachined tunneling accelerometer

High-precision miniature accelerometers based on electron tunneling transducers have been successfully fabricated using bulk-silicon micromachining process. This process has been modified to reduce bi-metal effects and results in greatly-suppressed 1/f noise. A comprehensive system model and a robust controller based on mixed /spl mu/ synthesis have also been developed to close the feedback loop, extend the bandwidth, and withstand accelerometer variations due to micromachining process variations. This accelerometer is a prototype intended for underwater acoustics applications and is designed to be packaged in an 8 cm/sup 3/ sphere volume with a total mass of 8 grams. In this paper, we describe the accelerometer design, the feedback control design, and several performance enhancements of these micromachined tunneling accelerometers, which include a high resolution of 20 nano-g//spl radic/Hz and a 5 Hz-1.5 kHz bandwidth.