Advanced Receive Channel Architecture
First Claim
1. A method of scanning a touch sensor panel, comprising:
- demodulating a summation of a first plurality of signals received from a plurality of sense lines of the touch sensor panel with a plurality of sample frequency signals using a first plurality of signal mixers; and
demodulating a second plurality of signals received from the plurality of sense lines with a demodulation frequency using the plurality of signal mixers;
wherein the first plurality of signal mixers perform demodulation in multiple time periods.
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Abstract
This relates to an architecture of a receive channel circuit used during both a spectrum analysis phase and a touch panel detection phase. Various components of the receive channel can be used during both the spectrum analysis phase and the touch panel detection phase. For example, a plurality of digital signal mixers used in the receive channel circuit can be used to demodulate signals during both a spectrum analysis phase and a touch sensor panel detection phase. In addition, the number of digital mixers needed in the receive channel can be reduced by dividing groups of signals to be demodulated into multiple sets of signals and demodulating each set at different times. Furthermore, the size of a sine look-up table (LUT) used to generate sine waveforms can be reduced by taking advantage of the symmetry of the sine waveform. For example, a quarter of a sine waveform can be saved in the LUT and the remaining quadrants of the waveform can be derived based on the symmetry of the sine wave.
105 Citations
39 Claims
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1. A method of scanning a touch sensor panel, comprising:
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demodulating a summation of a first plurality of signals received from a plurality of sense lines of the touch sensor panel with a plurality of sample frequency signals using a first plurality of signal mixers; and demodulating a second plurality of signals received from the plurality of sense lines with a demodulation frequency using the plurality of signal mixers; wherein the first plurality of signal mixers perform demodulation in multiple time periods. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for obtaining a plurality of values used to generate an image of touch on a touch sensor panel, comprising:
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generating one or more sine waveforms based on values stored in a sine look-up table (LUT), the sine LUT storing values representative of a quarter of each of the sine waveforms, wherein the remainder three-quarters of each of the sine waveforms are derived based on a symmetry of each of the sine waveforms; and demodulating a plurality of signals received from a sense lines of the touch sensor panel by mixing the plurality of signals with one or more of the sine waveforms. - View Dependent Claims (13, 14, 15)
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16. An apparatus for obtaining a plurality of values used to generate an image of touch from a touch sensor panel, comprising:
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a plurality of analog-to-digital converts (ADCs), each ADC configured to receive an analog signal from a different sense line of the touch sensor panel and covert the signal into a digital signal; a waveform generator circuit operable to generate signals having different waveforms; a summation circuit couplable to the plurality of ADCs and operable to generate a sum representative of a summation of the digital signals from the plurality of ADCs; and a plurality of signal mixers, wherein, during a first phase, the plurality of mixers are configured to mix each of a plurality of signals having different waveforms generated by the waveform generator with the sum signal representative of the summation of the ADC outputs, and wherein, during a second phase, the plurality of mixers are configured to mix each of the signals outputted from the plurality of ADCs with at least one signal generated by the waveform generator. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. An apparatus comprising:
a waveform generator circuit operable to generate signals having different waveforms, the waveform generator circuit having a sine look-up table (LUT) having a plurality of entries representative of characteristics of less than complete sine waveforms, wherein the waveform generator is operable to derive the remaining portions of the less than complete sine waveforms based on a symmetry of each of the sine waveforms. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37)
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38. A mobile telephone including an apparatus for obtaining a plurality of values used to generate an image of touch from a touch sensor panel, the apparatus comprising:
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a waveform generator circuit operable to generate signals having different waveforms; a summation circuit operable to generate a sum representative of a summation of a plurality of sense line outputs of the touch sensor panel; and a plurality of signal mixers, wherein, during a first phase, the plurality of mixers are configured to mix each of a plurality of signals having different waveforms generated by the waveform generator with the sum representative of the summation of the sense line outputs, and wherein, during a second phase, the plurality of mixers are configured to mix each of a plurality of sense line outputs with at least one signal generated by the waveform generator.
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39. A digital audio player including an apparatus for obtaining a plurality of values used to generate an image of touch from a touch sensor panel, the digital audio player comprising a waveform generator circuit operable to generate signals having different waveforms, the waveform generator circuit having a sine look-up table (LUT) storing a plurality of entries representative of characteristics of one or more incomplete sine waveforms, and wherein the waveform generator is operable to derive the remaining portions of the incomplete sine waveform so as to generate a complete sine waveform based on a symmetry of the sine waveform.
Specification