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US 2017/0370976 A1Published application
Capacitor sensor apparatus and sensing method thereof
AssigneeHimax Technologies Limited
InventorsChang-Hui Lin, Yaw-Guang Chang
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Abstract
A capacitor sensor apparatus and a sensing method thereof are provided. Oscillation signals with different frequencies are provided to a driving circuit and a mixer separately. The mixer mixes the oscillation signal with a lower frequency with a band-pass filtered signal. A band-pass filtering operation for generating the band-pass filtered signal is performed on a sensing signal before the mixer performs the mixing operation.
Claims8
A capacitor sensor apparatus, comprising:
- a capacitor sensing circuit;
- a driving circuit, coupled to the capacitor sensing circuit, and generating a driving signal to the capacitor sensing circuit according to a first oscillation signal with a first reference frequency to make the capacitor sensing circuit generating a sensing signal;
- a band-pass filter circuit, coupled to the capacitor sensing circuit, and performing band-pass filtering to the sensing signal to generate a band-pass filtered signal;
- a mixer, coupled to the band-pass filtering circuit, and mixing a second oscillation signal with a second reference frequency with the band-pass filtered signal to generate a mixed signal, wherein the first reference frequency is greater than the second reference frequency;
- a low-pass filter circuit, coupled to the mixer, and performing low-pass filtering to the mixed signal to generate a low-pass filtered signal;
- an analog-to-digital converter, coupled to the low-pass filter circuit, and converting the low-pass filtered signal into a digital signal;
- and
- a signal processing circuit, coupled to the analog-to-digital converter, and calculating a capacitance sensing amount of the capacitor sensing circuit according to the digital signal.
5 more elements
A sensing method for a capacitor sensor apparatus, comprising:
- generating a driving signal to a capacitor sensing circuit according to a first oscillation signal with a first reference frequency, so as to make the capacitor sensing circuit to generate a sensing signal;
- performing band-pass filtering to the sensing signal to generate a band-pass filtered signal;
- mixing a second oscillation signal with a second reference frequency with the band-pass filtered signal to generate a mixed signal, wherein the first reference frequency is greater than the second reference frequency;
- performing low-pass filtering to the mixed signal to generate a low-pass filtered signal;
- converting the low-pass filtered signal into a digital signal;
- and
- calculating a capacitance sensing amount of the capacitor sensing circuit according to the digital signal.
4 more elements
Dependencies are inferred from the claim text.