Abstract: A variable area capacitor with a flexible electrode responsive to a physical effect and a rigid electrode with a predetermined surface contour. The surface contour is dimensioned to provide a specific change in capacitance with deflection of the flexible electrode. A thin dielectric layer maintains a substantially fixed spacing between the two electrodes. Preferred embodiments include a pressure sensor, microphone and accelerometer. A differential transconductance amplifier detects changes of the variable capacitor in a low-impedance, bridge-like circuit and feeds back current to balance the bridge. The voltage that controls the feedback current is proportional to capacitance over a wide dynamic range.
Type:
Grant
Filed:
March 10, 1998
Date of Patent:
November 28, 2000
Assignee:
Horizon Technology Group
Inventors:
Robert B. McIntosh, Philip E. Mauger, Steven R. Patterson, Gene A. Goodman