Capacitance detection circuit, capacitance detection method, touch detection apparatus, and terminal device

A capacitance detection method, applied to a capacitance detection circuit, the method comprising:

• converting, by each of at least N−1 first front end circuits, capacitance signals of two connected capacitors to be detected into first voltage signals, and performing differencing on the first voltage signals of the two connected capacitors to be detected, to obtain a first differential signal of voltages corresponding to the two connected capacitors to be detected, the N being greater than or equal to 2;
• converting, by each of at least one second front end circuit, capacitance signals of a connected capacitor to be detected and a connected reference capacitor into second voltage signals, and performing differencing on the second voltage signal of the connected capacitor to be detected and the second voltage signal of the connected reference capacitor, to obtain a second differential signal of voltages corresponding to the connected capacitor to be detected and the connected reference capacitor;
• and
• determining, by a processing circuit according to the first differential signal obtained by each of the first front end circuits and the second differential signal obtained by each of the second front end circuits, a capacitance value of each of N capacitors to be detected.

A touch detection apparatus comprising:

• a capacitance detection circuit for detecting capacitances of N capacitors to be detected, the N being greater than or equal to 2, wherein the capacitance detection circuit comprises a reference capacitor, at least N−1 first front end circuits for converting capacitance signals of the capacitors to be detected into first voltage signals and performing differencing on the first voltage signals, at least one second front end circuit for converting capacitance signals of a capacitor to be detected and the reference capacitor into second voltage signals and performing differencing on the second voltage signals, and a processing circuit, wherein:
• each of the at least N−1 first front end circuits comprises a first input end and a second input end, and each of the at least one second front end circuit comprises a third input end and a fourth input end;
• a first input end and a second input end of each of at least N−2 first front end circuits are respectively connected to two different capacitors to be detected;
• a first input end of a first front end circuit except the at least N−2 first front end circuits is simultaneously connected to a third input end of a second front end circuit and a capacitor to be detected, a second input end of the first front end circuit except the at least N−2 first front end circuits is simultaneously connected to a first input end of a first front end circuit of the at least N−2 first front end circuits and a capacitor to be detected, and the capacitors to be detected to which the two input ends of the first front end circuit except the at least N−2 first front end circuits are connected are different capacitors to be detected;
• a third input end of each of the at least one second front end circuit is connected to a capacitor to be detected, and a fourth input end of each of the at least one second front end circuit is connected to the reference capacitor, the other end of the reference capacitor is connected to ground;
• each of the at least N−1 first front end circuits outputs a first differential signal of voltages corresponding to two connected capacitors to be detected;
• each of the at least one second front end circuit outputs a second differential signal of voltages corresponding to a connected capacitor to be detected and connected the reference capacitor;
• the processing circuit is connected to output ends of each of the first front end circuits and each of the second front end circuits, and is configured to determine, according to the first differential signal output by each of the first front end circuits and the second differential signal output by each of the second front end circuits, a capacitance value of each of the N capacitors to be detected;
• and
• the touch detection apparatus determines a touch position of a user according to a capacitance value of each of N capacitors to be detected determined by the capacitance detection circuit.