Vibration analyzing device

摘要

A microelectronic device to detect mechanical vibrations and analyze vibration frequencies. The device comprises a vibrator in the form of thin plate supported on a semiconductor substrate in the manner of either cantilever beam or fixed beam. The vibrator is either conductive or coated with a conductive film to serve as a vibratable electrode layer. The substrate is formed with a fixed electrode layer in an area opposite to the vibrator, and an electric circuit to detect a change in the capacitance between the fixed and vibratable electrode layers is integrated with the substrate. For discrimination of vibration frequencies without using any bandpass filter, the device may have a plurality of vibrators different in resonance frequency each paired with a fixed electrode layer. To make the device sharply responsive to specific frequencies within a very narrow range, two vibrators slightly different in resonance frequency are arranged close to each other, and changes in the capacitances of two variable capacitors respectively provided by the two vibrators are detected combinedly.