Abstract
A capacitance sensor, having at least one electrode is disclosed. A frequency spread signal generation circuit is coupled to the at least one electrode to apply a frequency spread signal based on a spread sequence. A periodic signal with a frequency is coupled to the at least one electrode. A frequency controller is coupled to the frequency spread signal generation circuit to vary the frequency of the periodic signal. A receiver circuit is coupled to the at least one or a further electrode to receive a version of the frequency spread signal which depends on a capacitance applied to the at least one electrode. An evaluation circuit is coupled to the receiver circuit to determine a capacitance value based on the received, dependent version of the frequency spread signal.
| Original language | English |
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| Patent number | US2009243633 |
| IPC | G01R 27/ 26 A I |
| Priority date | 6/12/07 |
| Publication status | Published - 1 Oct 2009 |