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A new sigma-delta capacitive touch detection circuit

A technology of capacitive touch and detection circuit, applied in the direction of capacitance measurement, measurement of resistance/reactance/impedance, measurement device, etc., can solve problems such as poor self-adaptive ability, achieve strong self-adaptive ability, reduce changes, and save costs

Active Publication Date: 2020-12-15
湖南品腾电子科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the traditional sigma-delta capacitive touch detection (referred to as CSD-CapSense Sigma Delta) scheme can only adapt to the size of the external touch capacitor by adjusting the discharge resistance. There is also the effect of mutual capacitance between capacitors

Method used

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  • A new sigma-delta capacitive touch detection circuit
  • A new sigma-delta capacitive touch detection circuit
  • A new sigma-delta capacitive touch detection circuit

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Embodiment Construction

[0020] The circuit block diagram of the new capacitive touch detection circuit proposed by the present invention is as follows: figure 2 as shown,

[0021] The specific circuit diagram is attached image 3 And attached Figure 4 shown, contains two circuit modes, attached image 3 Touch detection for touch capacitor discharge mode, attached Figure 4 Touch detection is performed for the charging mode of the touch capacitor. The difference between the two lies in the additional figure 2 In the charging mode shown, the touch capacitor charges the modulation capacitor through the switch circuit, and the attached image 3 In the discharge mode shown, the touch capacitor discharges the modulation capacitor through the switch circuit, where C MOD_IN It is an internal small modulation capacitor, which can be MIM capacitor or MOS capacitor.

[0022] Compared with the traditional CSD, an initialization module is added, and most importantly, a new capacitive-to-current input mod...

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Abstract

The invention discloses a novel sigma-delta capacitive touch testing circuit which is characterized in that the circuit comprises a capacitance-to-current input module, an initializing module, a sigma-delta modulator module and a counter module. The novel sigma-delta capacitive touch testing circuit utilizes a successive approximation adaptive current source and has high adaptive capability. An inner circuit parameter can be adjusted in real time according to the external touch capacitance. Sensitivity of the testing circuit can be kept unchanged. Furthermore cost can be saved, and influence of mutual capacitance between different touch capacitors is eliminated.

Description

technical field [0001] The invention relates to the technical field of touch detection, in particular to a novel sigma-delta capacitive touch detection circuit. Background technique [0002] The first-order Sigma-Delta modulator structure in the prior art is as attached figure 1 As shown, it consists of a summing adder, an integrator, a 1-bit ADC (latch comparator) and a 1-bit DAC. Through oversampling and noise shaping techniques, the signal-to-noise ratio of the data converter can be improved. Utilizing the high signal-to-noise ratio of the output of the Sigma Delta modulator, it can be used to detect the size of the capacitance, especially the touch capacitance. The change of touch capacitance is converted into the change of current, input to the first-order sigma-delta ADC, and the digital code that can represent the size of the touch capacitance is output through the ADC, so that the change of touch capacitance can be obtained, and the purpose of detecting touch capaci...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R27/26
CPCG01R27/2605
Inventor 谷洪波
Owner 湖南品腾电子科技有限公司