公开(公告)号：US20190285438A1

公开(公告)日：2019-09-19

申请号：US16354449

申请日：2019-03-15

Applicant: Cirrus Logic International Semiconductor Ltd.

Inventor： Mengde WANG ,  Zhong YOU

IPC: G01D5/24

Abstract: Embodiments described herein relate to methods and apparatus for separating an interference signal from a carrier signal for sensing a capacitance of a capacitive sensor. An analog front end, AFE, circuit for a capacitive sensor comprises an input configured to receive an input signal from the capacitive sensor, wherein the input signal comprises a carrier signal and an interference signal; a first signal path between the input and an output configured to output an output signal, wherein the first signal path is configured with a first impedance at a frequency of the interference signal; and a second signal path coupled to the input, wherein the second signal path is configured with a second impedance at the frequency of the interference signal, wherein the second impedance is lower than the first impedance so as to reduce a voltage swing caused by the interference signal at the input.