SENSE AMPLIFIER STABILIZATION WITH SWITCHED SERIES RESISTOR
First Claim
1. A touch sensing apparatus comprising:
- a sense channel configured to receive input from one or more electrodes, the sense channel comprising a sense amplifier and a variable resistance circuit, the variable resistance circuit coupled to an input of the sense amplifier and in series with the sense amplifier; and
logic configured to;
couple the sense channel to the one or more electrodes; and
adjust an effective resistance of the variable resistance circuit to satisfy one or more stability conditions for the sense amplifier.
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Accused Products
Abstract
A sense amplifier can be designed with a series variable resistance circuit to dynamically adjust an input resistance in series with the sense amplifier for stability during the different operating modes. In some examples, a switchable resistor can be switched into the input path of the sense amplifier for stability when required by increased capacitive loading of the sense electrodes, and can be switched out of the input path of the sense amplifier when unnecessary for stability. In some examples, an adjustable resistor can be coupled to and in series with the input of the sense amplifier. The resistance of the adjustable resistor can be tuned to stabilize the sense amplifier during operating modes having increased capacitive loading from the sense electrodes and can be minimized when additional input resistance is unnecessary for stability.
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Citations
26 Claims
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1. A touch sensing apparatus comprising:
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a sense channel configured to receive input from one or more electrodes, the sense channel comprising a sense amplifier and a variable resistance circuit, the variable resistance circuit coupled to an input of the sense amplifier and in series with the sense amplifier; and logic configured to; couple the sense channel to the one or more electrodes; and adjust an effective resistance of the variable resistance circuit to satisfy one or more stability conditions for the sense amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for scanning a touch sensor panel, the method comprising:
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configuring a plurality of sense channels for a coarse scan operation, wherein each of the sense channels configured for the coarse scan operation includes an adjustable resistance in series with an input path of a sense amplifier; performing the coarse scan operation; configuring the plurality of sense channels for a fine scan operation, wherein the adjustable resistance in series with the input path of the sense amplifier is reduced for each of the sense channels configured for the fine scan operation; and performing the fine scan operation. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A non-transitory computer readable storage medium containing instructions that, when executed by a processor, can perform a method for scanning a touch sensor panel, the method comprising:
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configuring a plurality of sense channels for a coarse scan operation, wherein each of the sense channels configured for the coarse scan operation includes an adjustable resistance in series with an input path of a sense amplifier; performing the coarse scan operation; configuring the plurality of sense channels for a fine scan operation, wherein the adjustable resistance in series with the input path of the sense amplifier is reduced for each of the sense channels configured for the fine scan operation; and performing the fine scan operation. - View Dependent Claims (22, 23, 24, 25)
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26. A touch sensing apparatus comprising:
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a sense channel configured to receive input from one or more electrodes, the sense channel comprising a sense amplifier and means for adjusting an input resistance coupled to an input of the sense amplifier and in series with the sense amplifier; means for coupling the sense channel to the one or more electrodes; and means for adjusting the input resistance to satisfy one or more stability conditions for the sense amplifier.
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Specification