ASYNCHRONOUS INTERFERENCE DETECTION IN A CAPACITIVE SENSING SYSTEM

摘要

In an example, a processing system for a capacitive sensing device includes a sensor module and a determination module. The sensor module comprises a receiver, coupled to a sensor electrode, configured to receive a capacitive sensing signal. The receiver includes an in-phase channel and a quadrature channel. The in-phase channel is configured to mix the capacitive sensing signal with a local oscillator signal substantially in phase with the capacitive sensing signal. The quadrature channel is configured to mix the capacitive sensing signal with a phase-shifted signal near ninety degrees out of phase with the capacitive sensing signal. The determination module is configured to measure a change in capacitance in response to a demodulated signal of the in-phase channel concurrently with measuring a non-coherent signal in response to a demodulated signal of the quadrature channel.

主权项

1. A processing system for a capacitive sensing device, comprising:
a sensor module comprising a receiver, coupled to a sensor electrode, configured to receive a capacitive sensing signal, the receiver including:
an in-phase channel configured to mix the capacitive sensing signal with a local oscillator signal substantially in phase with the capacitive sensing signal; anda quadrature channel configured to mix the capacitive sensing signal with a phase-shifted signal near ninety degrees out of phase with the capacitive sensing signal; and a determination module configured to measure a change in capacitance in response to a demodulated signal of the in-phase channel concurrently with measuring a non-coherent signal in response to a demodulated signal of the quadrature channel.