Capacitance detection circuit, detection chip and electronic device

A detection chip, comprising a capacitance detection circuit, the capacitance detection circuit comprised:

• a first drive module, a conversion module, a processing module, and a control module;
• the first drive module being configured to supply a first voltage to a first capacitor to be measured to charge the first capacitor to be measured;
• the conversion module being configured to perform charge conversion processing on the first capacitor to be measured to generate an output voltage, the conversion module comprising a first suppression module, the control module being configured to control the first suppression module to suppress an interference signal with a frequency that is less than a first frequency or greater than a second frequency when the conversion module generates the output voltage, and the second frequency being greater than the first frequency;
• and the processing module being configured to determine a capacitance change before and after the first capacitor to be measured is affected by an applied electric field based on the output voltage;
• wherein the conversion module has a first input terminal and a second input terminal, the first input terminal of the conversion module is electrically connected to the first drive module, and the second input terminal of the conversion module is connected to a common mode voltage;
• wherein the conversion module comprises a differential amplifier, the first input terminal of the conversion module is an inverting input terminal of the differential amplifier, the second input terminal of the conversion module is a non-inverting input terminal of the differential amplifier, the first drive module is electrically connected to the inverting input terminal of the differential amplifier, the non-inverting input terminal of the differential amplifier is connected to the common mode voltage, and an output terminal of the differential amplifier is electrically connected to the processing module, and two terminals of the first suppression module are respectively connected to the inverting input terminal and the output terminal of the differential amplifier;
• wherein the first suppression module comprises a first switch unit, a first capacitor, and a second capacitor, wherein the first switch unit comprises a first terminal, a second terminal and a third terminal, the first terminal and the second terminal of the first switch unit being directly connected to the inverting input terminal and the output terminal of the differential amplifier respectively, and the third terminal of the first switch unit being connected to a first terminal of the first capacitor;
• a second terminal of the first capacitor is grounded;
• and two terminals of the second capacitor are directly connected to the inverting input terminal and the output terminal of the differential amplifier respectively;
• and the control module is configured to control the first switch unit to switch between a first closed state in which the third terminal contacts the first terminal and a second closed state in which the third terminal contacts the second terminal, such that the first capacitor is alternately connected to the first terminal of the first switch unit and the second terminal of the first switch unit to suppress an electrical signal which has a frequency less than the first frequency, a switching frequency of the first switch unit being greater than twice a driving frequency.

An electronic device, comprising:

• a detection chip, the detection chip comprised a capacitance detection circuit, the capacitance detection circuit comprised:
• a first drive module, a conversion module, a processing module, and a control module;
• the first drive module being configured to supply a first voltage to a first capacitor to be measured to charge the first capacitor to be measured;
• the conversion module being configured to perform charge conversion processing on the first capacitor to be measured to generate an output voltage, the conversion module comprising a first suppression module, the control module being configured to control the first suppression module to suppress an interference signal with a frequency that is less than a first frequency or greater than a second frequency when the conversion module generates the output voltage, and the second frequency being greater than the first frequency;
• and the processing module being configured to determine a capacitance change before and after the first capacitor to be measured is affected by an applied electric field based on the output voltage;
• wherein the conversion module has a first input terminal and a second input terminal, the first input terminal of the conversion module is electrically connected to the first drive module, and the second input terminal of the conversion module is connected to a common mode voltage;
• wherein the conversion module comprises a differential amplifier, the first input terminal of the conversion module is an inverting input terminal of the differential amplifier, the second input terminal of the conversion module is a non-inverting input terminal of the differential amplifier, the first drive module is electrically connected to the inverting input terminal of the differential amplifier, the non-inverting input terminal of the differential amplifier is connected to the common mode voltage, and an output terminal of the differential amplifier is electrically connected to the processing module, and two terminals of the first suppression module are respectively connected to the inverting input terminal and the output terminal of the differential amplifier;
• wherein the first suppression module comprises a first switch unit, a first capacitor, and a second capacitor, wherein the first switch unit comprises a first terminal, a second terminal and a third terminal, the first terminal and the second terminal of the first switch unit being directly connected to the inverting input terminal and the output terminal of the differential amplifier respectively, and the third terminal of the first switch unit being connected to a first terminal of the first capacitor;
• a second terminal of the first capacitor is grounded;
• and two terminals of the second capacitor are directly connected to the inverting input terminal and the output terminal of the differential amplifier respectively;
• and the control module is configured to control the first switch unit to switch between a first closed state in which the third terminal contacts the first terminal and a second closed state in which the third terminal contacts the second terminal, such that the first capacitor is alternately connected to the first terminal of the first switch unit and the second terminal of the first switch unit to suppress an electrical signal which has a frequency less than the first frequency, a switching frequency of the first switch unit being greater than twice a driving frequency.