Touch detection circuit, touch sensing chip and electronic device

A touch detection circuit, comprising:

• a charge/discharge circuit, which is coupled to a corresponding sense channel of a touch screen and is configured to charge or discharge the sense channel over a scanning period, thereby converting a sense signal on the sense channel into corresponding sense charge;
• a first-order N-bit delta-sigma analog-to-digital converter (ADC) comprising an adder, an integrator, an N-bit ADC and an N-bit digital-to-analog converter (DAC), the adder comprising two input terminals coupled respectively to an output terminal of the charge/discharge circuit and an output terminal of the N-bit DAC, the N-bit DAC comprising an input terminal coupled to an output terminal of the N-bit ADC, where N is an integer satisfying N≥2,
• wherein the integrator is configured to integrate net incoming charge that the integrator receives;
• the N-bit ADC is configured to quantize an output of the integrator into an N-bit digital signal;
• the N-bit DAC is configured to provide subtractive reference charge according to the instruction of the N-bit digital signal;
• and the adder is configured to derive the net incoming charge by subtracting the subtractive reference charge from the sense charge, and
• wherein the charge/discharge circuit comprises first, second, third switches and a current source, and wherein in a self-capacitance scan mode, a first terminal of the current source is coupled to a second power supply voltage, a second terminal of the current source is coupled to a first terminal of the second switch, a second terminal of the second switch is coupled to a first terminal of the first switch, a first terminal of the third switch and the sense channel, a second terminal of the first switch is coupled to a first power supply voltage, and a second terminal of the third switch is coupled to the input terminal of the adder.

A touch detection circuit, comprising:

• a charge/discharge circuit, which is coupled to a corresponding sense channel of a touch screen and is configured to charge or discharge the sense channel over a scanning period, thereby converting a sense signal on the sense channel into corresponding sense charge;
• a first-order N-bit delta-sigma analog-to-digital converter (ADC) comprising an adder, an integrator, an N-bit ADC and an N-bit digital-to-analog converter (DAC), the adder comprising two input terminals coupled respectively to an output terminal of the charge/discharge circuit and an output terminal of the N-bit DAC, the N-bit DAC comprising an input terminal coupled to an output terminal of the N-bit ADC, where N is an integer satisfying N≥2,
• wherein the integrator is configured to integrate net incoming charge that the integrator receives;
• the N-bit ADC is configured to quantize an output of the integrator into an N-bit digital signal;
• the N-bit DAC is configured to provide subtractive reference charge according to the instruction of the N-bit digital signal;
• and the adder is configured to derive the net incoming charge by subtracting the subtractive reference charge from the sense charge, and
• wherein the charge/discharge circuit comprises first, second, third switches and a current source, and wherein in a mutual capacitance scan mode, a first terminal of the current source is coupled to a first power supply voltage, a second terminal of the current source is coupled to a first terminal of the second switch, a second terminal of the second switch is coupled to a first terminal of the first switch, a first terminal of the third switch and the sense channel, a second terminal of the first switch is coupled to a common reference voltage, and a second terminal of the third switch is coupled to the input terminal of the adder.