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 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(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/root Hz and a 5 Hz-1.5 kHz bandwidth.