Analog front-end circuit and operating method for touch display device

Abstract

This invention provides an analog front-end circuit and its operation method for a touch display device. The analog front-end circuit includes a receiving circuit and an amplifying circuit. The receiving circuit receives a first noise located in the touch display device to generate an input signal. The amplifying circuit receives a touch sensing signal from the touch display device and also receives the input signal from the receiving circuit. The amplifying circuit uses the first noise to reduce a second noise in the touch sensing signal to generate an output signal.

Claims

1. An analog front-end circuit for a touch display device, comprising: A receiving circuit is configured to receive first noise located on the touch display device to generate an input signal; The amplifier circuit includes an amplification circuit, one end of which is connected to the receiving circuit to receive the input signal from the receiving circuit, and the other end of which receives the touch sensing signal from the touch display device. The amplification circuit uses the first noise to reduce the second noise in the touch sensing signal to generate an output signal. The first noise and the second noise are generated by voltage-coupled data signals from the cathode of the touch display device, respectively. The first noise and the second noise are generated at the falling edge and the rising edge of the data signal, respectively.

2. The analog front-end circuit as described in claim 1, wherein the cathode is connected to the receiving circuit and provides the first noise.

3. The analog front-end circuit as described in claim 1, wherein the amplifier circuit comprises: An operational amplifier, wherein a first input terminal of the operational amplifier receives the touch sensing signal, a second input terminal of the operational amplifier receives the input signal, and an output terminal of the operational amplifier is used to output the output signal; And a feedback circuit, connected between the first input terminal and the output terminal of the operational amplifier.

4. The analog front-end circuitry as described in claim 3, wherein the receiving circuitry comprises: A switch, wherein the first terminal of the switch receives a common-mode voltage, and the second terminal of the switch is connected to the second input terminal of the operational amplifier; And a capacitor, wherein a first end of the capacitor receives the first noise, and a second end of the capacitor is connected to the second input terminal of the operational amplifier.

5. The analog front-end circuit as claimed in claim 4, wherein during a first period, when the common-mode voltage is not yet driven by the data signal and is therefore free of noise, the switch is turned on to allow the second input of the operational amplifier to receive the common-mode voltage.

6. The analog front-end circuit as described in claim 5, wherein during a second period following the first period, the switch is turned off, and the first noise is coupled to the input signal.

7. The analog front-end circuitry as described in claim 3, wherein the receiving circuitry comprises: A first switch, the first terminal of the first switch receiving a common-mode voltage; A second switch, the first end of which is connected to the second end of the first switch, and the second end of the second switch is connected to the second input terminal of the operational amplifier; a third switch, the first end of which receives the first noise; a fourth switch, the first end of which is connected to the second end of the third switch, and the second end of the fourth switch is connected to a reference low voltage; and a capacitor, the first end of which is connected to the second end of the first switch and the first end of the second switch, and the second end of which is connected to the second end of the third switch and the first end of the fourth switch.

8. The analog front-end circuit as described in claim 7, wherein: During the first period, the second and third switches are turned off, and the first and fourth switches are turned on so that the second input terminal of the operational amplifier receives the common-mode voltage. In the second period following the first period, the first and fourth switches are turned off, and the second and third switches are turned on, and the first noise is coupled to the input signal.

9. The analog front-end circuit as claimed in claim 7, wherein during a first period: the second switch and the third switch are turned off during the period between a first time point and a second time point, the first switch and the fourth switch are turned on during the period between a third time point and a fourth time point, the first time point being earlier than the third time point, and the fourth time point being later than the third time point and earlier than the second time point.

10. A method of operating a touch display device, comprising: The receiving circuit receives a first noise located on the touch display device to generate an input signal; The amplifier circuit receives the input signal from the receiving circuit and the touch sensing signal from the touch display device. The amplifier circuit uses the first noise to reduce the second noise in the touch sensing signal to generate an output signal, wherein the first noise and the second noise are generated by voltage-coupled data signals of the cathode of the touch display device, and the first noise and the second noise are generated at the falling edge and the rising edge of the data signal, respectively.

11. The method of operation as described in claim 10, wherein the cathode is connected to the receiving circuit and provides the first noise.

12. The method of operation as described in claim 10, wherein the amplification circuit comprises: An operational amplifier, wherein a first input terminal of the operational amplifier receives the touch sensing signal, a second input terminal of the operational amplifier receives the input signal, and an output terminal of the operational amplifier is used to output the output signal; And a feedback circuit, connected between the first input terminal and the output terminal of the operational amplifier.

13. The method of operation as described in claim 12, wherein the receiving circuit comprises: A switch, wherein the first terminal of the switch receives a common-mode voltage, and the second terminal of the switch is connected to the second input terminal of the operational amplifier; And a capacitor, wherein a first end of the capacitor receives the first noise, and a second end of the capacitor is connected to the second input terminal of the operational amplifier.

14. The method of operation as described in claim 13, wherein the step of receiving the common-mode voltage to generate the input signal includes: During a first period, when the common-mode voltage is not yet driven by the data signal and therefore has no noise, the switch is turned on so that the second input terminal of the operational amplifier receives the common-mode voltage; and during a second period following the first period, the switch is turned off and the first noise is coupled to the input signal.

15. The method of operation as described in claim 12, wherein the receiving circuit comprises: A first switch, the first terminal of the first switch receiving a common-mode voltage; A second switch, the first end of which is connected to the second end of the first switch, and the second end of the second switch is connected to the second input terminal of the operational amplifier; a third switch, the first end of which receives the first noise; a fourth switch, the first end of which is connected to the second end of the third switch, and the second end of the fourth switch is connected to a reference low voltage; and a capacitor, the first end of which is connected to the second end of the first switch and the first end of the second switch, and the second end of which is connected to the second end of the third switch and the first end of the fourth switch.

16. The method of operation as described in claim 15, wherein the step of receiving the common-mode voltage to generate the input signal includes: During the first period, the second switch and the third switch are disconnected; The first switch and the fourth switch are turned on so that the second input terminal of the operational amplifier receives the common-mode voltage; and during a second period after the first period, the first switch and the fourth switch are turned off, and the second switch and the third switch are turned on so that the first noise is coupled to the input signal.

17. The method of operation as described in claim 15, wherein during a first period: the second switch and the third switch are turned off during the period between a first time point and a second time point; the first switch and the fourth switch are turned on during the period between a third time point and a fourth time point; the first time point is earlier than the third time point; and the fourth time point is later than the third time point and earlier than the second time point.

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