Capacitive sensing device with single reference channel

An input device, comprising:

• a plurality of sensor electrodes;
• and
• a processing system, coupled to the plurality of sensor electrodes, including a plurality of sensor channels coupled to the plurality of sensor electrodes and a single reference channel coupled to a reference transmitter through a reference capacitance, the reference channel comprising:
• a charge accumulation circuit having an input coupled to the reference transmitter through the reference capacitance and configured to generate an integrated signal;
• a demodulator circuit having an input coupled to an output of the charge accumulation circuit and configured to demodulate the integrated signal to generate at least one demodulated signal;
• a sampling circuit having an input coupled to an output of the demodulator circuit and configured to sample the at least one demodulated signal;
• a first reference buffer coupled to an output of the sampling circuit, the first reference buffer outputting a first voltage reference for the capacitive sensing device;
• and
• a second reference buffer coupled to the output of the sampling circuit, the second reference buffer outputting a second voltage reference for the capacitive sensing device.

A method of generating reference voltages for a capacitive sensing device, comprising:

• coupling a transmitter signal to a reference capacitance;
• integrating output of the reference capacitance to generate an integrated signal;
• demodulating the integrated signal to generate at least one demodulated signal;
• sampling the at least one demodulated signal;
• and
• buffering the sampled at least one demodulated signal to output a first voltage reference and a second voltage reference.