US Patent 10203809 Interference detection

An input device including: a first in-phase touch sensing block including: an analog mixer configured to mix a resulting signal associated with a capacitive sensor electrode with a local oscillator (LO) signal; an analog to digital converter (ADC) configured to convert an output of the analog mixer into a digital signal; and a first decimation filter configured to determine an in-phase component of an interference at a frequency of the LO signal based, at least in part, on the digital signal; and a first quadrature interference detection block including: a second decimation filter configured to determine a quadrature component of the interference at the frequency.