A high-precision, wide-bandwidth micromachined tunneling accelerometer

High-precision miniature accelerometers based on electron tunneling transdu cers have been successfully fabricated using bulk-silicon micromachining pr ocess. This process has been modified to reduce bi-metal effects and result s in greatly-suppressed 1/f noise. A comprehensive system model and a robus t controller based on mixed mu synthesis have also been developed to close the feedback loop, extend the bandwidth, and withstand accelerometer variat ions due to micromachining process variations. This accelerometer is a prot otype intended for underwater acoustics applications and is designed to be packaged in an 8 cm(3) sphere volume with a total mass of 8 grams. In this paper, we describe the accelerometer design, the feedback control design, a nd several performance enhancements of these micromachined tunneling accele rometers, which include a high resolution of 20 nano-g/root Hz and a 5 Hz-1 .5 kHz bandwidth.