TOUCH SENSING APPARATUS AND TOUCH SENSING METHOD
First Claim
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1. A touch sensing apparatus comprising:
- an excitation source, arranged to generate an excitation signal having a first frequency;
a capacitor under test, arranged to receive the excitation signal, and generate a sensing signal;
a sampling circuit, arranged to sample the sensing signal to generate a digital output, the sampling circuit comprising a pulse density modulation (PDM) unit that has an input end coupled to the capacitor under test,the pulse density modulation unit sampling a signal received at the input end with a second frequency to generate the digital output, wherein the second frequency is higher than the first frequency; and
a filter, coupled to the pulse density modulation unit, the filter arranged to filter the digital output to generate a filtered signal.
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Abstract
A touch sensing apparatus includes an excitation source, a capacitor under test, a sampling circuit and a filter. The excitation source is used to generate an excitation signal having a first frequency. The capacitor under test is used to receive the excitation signal, and generate a sensing signal. The sampling circuit is used to sample the sensing signal to generate a digital output. The sampling circuit includes a pulse density modulation unit operating at a second frequency to generate the digital output, wherein the second frequency is higher than the first frequency. The filter is coupled to the pulse density modulation unit, and arranged to filter the digital output.
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Citations
19 Claims
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1. A touch sensing apparatus comprising:
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an excitation source, arranged to generate an excitation signal having a first frequency; a capacitor under test, arranged to receive the excitation signal, and generate a sensing signal; a sampling circuit, arranged to sample the sensing signal to generate a digital output, the sampling circuit comprising a pulse density modulation (PDM) unit that has an input end coupled to the capacitor under test, the pulse density modulation unit sampling a signal received at the input end with a second frequency to generate the digital output, wherein the second frequency is higher than the first frequency; and a filter, coupled to the pulse density modulation unit, the filter arranged to filter the digital output to generate a filtered signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A touch sensing method, comprising:
providing an excitation signal having a first frequency to a capacitor under test to generate a sensing signal; performing a sampling step on the sensing signal, the sampling step comprising;
performing a pulse density modulation (PDM) at a second frequency to generate a digital output, wherein the second frequency is higher than the first frequency; and
filtering the digital output to generate a filtered signal.- View Dependent Claims (14, 15, 16, 17, 18, 19)
Specification