Noise detection circuit, self-capacitance detection method, touch chip, and electronic device

Patent metadata

Field	Value
Publication number	US-2022043531-A1
Application number	US-202117501623-A
Country	US
Kind code	A1
Filing date	Oct 14, 2021
Priority date	Aug 6, 2020
Publication date	Feb 10, 2022
Grant date	—

Abstract

Disclosed is a noise detection circuit comprising: a control module configured to control a drive module such that a to-be-detected capacitor is charged with a first voltage in a first period, and the control module controls a cancellation module such that a cancellation capacitor is charged with the first voltage in the first period, or such that both terminals of the cancellation capacitor are connected to the first voltage; the control module controls the cancellation module such that a first terminal of the to-be-detected capacitor is connected to a first terminal of the cancellation capacitor in a second period; the control module controls a charge transfer module such that charges of the to-be-detected capacitor and charges of the cancellation capacitor are converted in a third period to generate an output voltage; and a processing module configured to determine a noise value at least based on the output voltage.

First claim

What is claimed is:

1 . A noise detection circuit, comprising: a control module, a drive module, a cancellation module, a charge transfer module, and a processing module; wherein the drive module is connected to the cancellation module, the cancellation module is connected to the charge transfer module, the charge transfer module is connected to the processing module, and the control module is connected to the drive module, the cancellation module, and the charge transfer module,
wherein the control module is configured to control the drive module such that a to-be-detected capacitor is charged with a first voltage in a first period, and control the cancellation module such that a cancellation capacitor is charged with the first voltage in the first period, or such that both terminals of the cancellation capacitor are connected to the first voltage; the control module is configured to control the cancellation module such that a first terminal of the to-be-detected capacitor is connected to a first terminal of the cancellation capacitor in a second period; the control module is configured to control the charge transfer module such that charges of the to-be-detected capacitor and charges of the cancellation capacitor are converted in a third period to generate an output voltage; the first period, the second period, and the third period are consecutive in time, the charge transfer module comprises an amplifier; an inverting input terminal of the amplifier is connected to the first voltage; and the processing module is configured to determine a noise value at least based on the output voltage.

2 . The noise detection circuit according to claim 1 , wherein the first voltage is a common mode voltage.

3 . The noise detection circuit according to claim 1 , wherein the drive module comprises a first switch unit, and the control module is further configured to control the first switch unit to be in a closed state, such that the drive module charges the to-be-detected capacitor with the first voltage in the first period;
wherein when the first switch unit is in the closed state, the first terminal of the to-be-detected capacitor is connected to the first voltage, and a second terminal of the to-be-detected capacitor is connected to a ground voltage.

4 . The noise detection circuit according to claim 3 , wherein the cancellation module comprises a second switch unit and the cancellation capacitor, and the control module is further configured to control the second switch unit to be in a closed state in the first period;
wherein when the second switch unit is in the closed state, the cancellation capacitor is charged, the first terminal of the cancellation capacitor is connected to the first voltage, and a second terminal of the cancellation capacitor is connected to the ground voltage; or wherein when the second switch unit is in the closed state, the first terminal of the cancellation capacitor is connected to the first voltage, and the second terminal of the cancellation capacitor is connected to the first voltage.

5 . The noise detection circuit according to claim 4 , wherein the cancellation module further comprises a third switch unit, and the control module is further configured to control the third switch unit to be in a closed state in the second period such that the first terminal of the to-be-detected capacitor is connected to the first terminal of the cancellation capacitor;
wherein when the third switch unit is in the closed state, the first terminal of the cancellation capacitor is disconnected from the first voltage, and the first terminal of the to-be-detected capacitor is disconnected from the first voltage.

6 . The noise detection circuit according to claim 1 , wherein when the charges of the to-be-detected capacitor and the charges of the cancellation capacitor are being converted, the first terminal of the to-be-detected capacitor, the first terminal of the cancellation capacitor, and a non-inverting input terminal of the amplifier are being connected.

7 . The noise detection circuit according to claim 1 , wherein the control module controls the charge transfer module to reset the charge transfer module in a fourth period; wherein the first period, the second period, the third period, and the fourth period are consecutive in time.

8 . The noise detection circuit according to claim 7 , wherein the charge transfer module further comprises a fourth switch unit, and the fourth switch unit is in a closed state in the third period such that the charges of the to-be-detected capacitor and the charges of the cancellation capacitor are converted to generate the output voltage; and the fourth switch unit is in an off state in the fourth period to reset the charge transfer module.

9 . The noise detection circuit according to claim 7 , wherein in the first period, a voltage of the to-be-detected capacitor is increased to the first voltage, a voltage of the cancellation capacitor is increased to the first voltage or a voltage of the cancellation capacitor is 0; a connection state of the second terminal of the cancellation capacitor in the second period is the same as a connection state of the second terminal of the cancellation capacitor in the first period; an output voltage of the charge transfer module is increased or reduced to 0 in the first period and the second period, and the output voltage of the charge transfer module is reduced or increased to 0 in the fourth period.

10 . The noise detection circuit according to claim 7 , wherein the processing module comprises a filter, an analog-to-digital converter, and a digital signal processor; wherein the filter filters the output voltage of the charge transfer module; the analog-to-digital converter performs analog-to-digital conversion on the filtered output voltage; the digital signal processor is configured to demodulate the output voltage after the analog-to-digital conversion at a reference frequency that is a reciprocal of a noise detection cycle; the noise detection cycle is equal to an integer multiple of a noise detection half cycle, and the noise detection half cycle is a sum of the first period, the second period, the third period, and the fourth period; or the noise detection half cycle is a sum of the first period, the second period, and the third period.

11 . The noise detection circuit according to claim 1 , wherein the drive module comprises a thirteenth switch unit, a fourteenth switch unit, and a nineteenth switch unit; the control module is further configured to control the thirteenth switch unit, the fourteenth switch unit, and the nineteenth switch unit to perform noise detection or self-capacitance detection; during the noise detection, the control module is configured to control the nineteenth switch unit such that the first terminal of the to-be-detected capacitor is connected to the first voltage in the first period; during the self-capacitance detection, the control module is configured to control the thirteenth switch unit and the fourteenth switch unit such that the first terminal of the to-be-detected capacitor is connected to a ground voltage or a power supply voltage; and a second terminal of the to-be-detected capacitor is connected to the ground voltage.

12 . The noise detection circuit according to claim 11 , wherein the cancellation module comprises a fifteenth switch unit, a sixteenth switch unit, a twentieth switch unit, a seventeenth switch unit, an eighteenth switch unit, and a twenty-first switch unit; the control module is further configured to control the fifteenth switch unit, the sixteenth switch unit, the twentieth switch unit, the seventeenth switch unit, the eighteenth sw

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• Tang Zhi
• Jiang Hong
• Chen Zhe

Classifications

• G06F3/044

  by capacitive means · CPC title

• G06F3/04166

  Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184) · CPC title

• G06F3/04182 Primary

  Filtering of noise external to the device and not generated by digitiser components · CPC title

• G06F3/0418 Primary

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G06F3/0445

  using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer · CPC title