US Patent:
20140049273, Feb 20, 2014
Inventors:
Marko Rocznik - Cupertino CA, US
Assignee:
ROBERT BOSCH GMBH - Stuttgart
International Classification:
G01R 27/26
Abstract:
A sensor includes a variable capacitor, a fixed capacitor, an inductor, a switch that electrically connects the variable capacitor with the inductor or the fixed capacitor with the inductor, an oscillator that generates a periodic signal, and a controller connected to the switch, the oscillator, and the inductor. The controller operates the switch, identifies a frequency of a first oscillation of the variable capacitor and the inductor based on the periodic signal from the oscillator, identifies a frequency of a second oscillation of the fixed capacitor and the inductor based on the periodic signal from the oscillator, and identifies a capacitance of the variable capacitor based on a ratio of the frequency of the first oscillation to the frequency of the second oscillation.