Programmable Integrated Circuit Device to Support Inductive Sensing
First Claim
1. An integrated circuit device configured as a programmable analog front end for supporting inductive touch sensing, said integrated circuit device comprising:
- a voltage reference;
a synchronous detector havinga first input coupled to an inductive reference coil external connection, wherein the inductive reference coil external connection is adapted for coupling to an inductive reference coil;
a second input coupled to an inductive touch sensor coil external connection, wherein the inductive touch sensor coil external connection is adapted for coupling to at least one inductive touch sensor coil;
a third input coupled to a reference select external connection, wherein the reference select external connection is adapted for coupling to a reference select signal;
a fourth input coupled to a clock external connection, wherein the clock external connection is adapted for coupling to a clock signal, anda fifth input coupled to the voltage reference;
a coil driver havingan output coupled to a coil drive output external connection,an input coupled to a coil drive input external connection;
an amplifier configured with a low-pass filter and having inputs coupled to the synchronous detector and an output having voltage values representative of inductance values of the at least one inductive touch sensor coil and the inductive reference coil, the output of the amplifier is coupled to a voltage detector output external connection; and
an interface and control module having a communications port, wherein the interface and control module controls at least one characteristic of the programmable analog front end;
wherein the synchronous detector mixes the clock signal with a signal from the inductive reference coil or the at least one inductive touch sensor coil, as selected by the reference select signal, to produce sum and difference mixing products, whereby the amplifier amplifies the sum and difference mixing products and substantially attenuates the sum mixing product and passes the difference mixing product at the output of the amplifier.
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Accused Products
Abstract
An integrated circuit device inductive touch analog front end excites selected ones of a plurality of inductive touch sensors and provides analog output signals representative of voltages across the coils of the plurality of inductive touch sensors. Various characteristics of the inductive touch analog front end are programmable. A digital processor controls selection of each one of the plurality of inductive touch sensors and receives the respective analog output voltage signal from the inductive touch AFE. The digital processor may program the characteristics of the inductive touch analog front end. When a sufficient change in the coil voltage is determined by the digital processor, that inductive touch sensor is assumed to have been actuated and the digital processor takes action based upon which one of the plurality of inductive touch sensors was actuated (touched).
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Citations
32 Claims
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1. An integrated circuit device configured as a programmable analog front end for supporting inductive touch sensing, said integrated circuit device comprising:
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a voltage reference; a synchronous detector having a first input coupled to an inductive reference coil external connection, wherein the inductive reference coil external connection is adapted for coupling to an inductive reference coil; a second input coupled to an inductive touch sensor coil external connection, wherein the inductive touch sensor coil external connection is adapted for coupling to at least one inductive touch sensor coil; a third input coupled to a reference select external connection, wherein the reference select external connection is adapted for coupling to a reference select signal; a fourth input coupled to a clock external connection, wherein the clock external connection is adapted for coupling to a clock signal, and a fifth input coupled to the voltage reference;
a coil driver havingan output coupled to a coil drive output external connection, an input coupled to a coil drive input external connection; an amplifier configured with a low-pass filter and having inputs coupled to the synchronous detector and an output having voltage values representative of inductance values of the at least one inductive touch sensor coil and the inductive reference coil, the output of the amplifier is coupled to a voltage detector output external connection; and an interface and control module having a communications port, wherein the interface and control module controls at least one characteristic of the programmable analog front end; wherein the synchronous detector mixes the clock signal with a signal from the inductive reference coil or the at least one inductive touch sensor coil, as selected by the reference select signal, to produce sum and difference mixing products, whereby the amplifier amplifies the sum and difference mixing products and substantially attenuates the sum mixing product and passes the difference mixing product at the output of the amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An electronic system having an inductive touch interface, said system comprising:
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an inductive touch interface comprising a plurality of inductive touch sensor coils and an inductive reference coil; a first integrated circuit digital processor; a second integrated circuit programmable inductive touch analog front end comprising; a voltage reference; a synchronous detector having a first input coupled to the inductive reference coil; a second input coupled to the plurality of inductive touch sensor coils; a third input coupled to a reference select signal from the digital processor; a fourth input coupled to a clock signal from the digital processor, and a fifth input coupled to the voltage reference; a coil driver having an output coupled in series with the inductive reference coil and selected ones of the plurality of inductive touch sensor coils, an input coupled through an external low-pass filter to a clock output from the digital processor; an amplifier configured with a low-pass filter and having inputs coupled to the synchronous detector and an output having voltage values representative of inductance values of the plurality of inductive touch sensor coils and the inductive reference coil, the output of the amplifier is coupled to an analog input of the digital processor; and an interface and control module having a communications port, wherein the interface and control module controls at least one characteristic of the programmable inductive touch analog front end; wherein the synchronous detector mixes the clock signal with a signal from the inductive reference coil or the at least one inductive touch sensor coil, as selected by the reference select signal, to produce sum and difference mixing products, whereby the amplifier amplifies the sum and difference mixing products and passes the difference mixing product at the output of the amplifier. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification