Time-averaged proximity sensor

A capacitive proximity sensor in a portable connected wireless device that includes a radio transmitter, the capacitive proximity sensor comprising a processing circuit configured to acquire a capacitance of a sense electrode and subtract drift and noise contributions from the capacitance and generate a digital variable that indicates that the sense electrode has detected a part of a user's body, an averaging unit including a FIFO buffer that is periodically supplied, following an update rate, with values of the digital variable, wherein the averaging unit is configured to produce an average value by averaging or accumulating values of the digital variable in the FIFO buffer within a time window that has a length of more than one minute, wherein the length of the time window is determined by a depth of the FIFO buffer and by the update rate, and a decision unit setting a time-averaged proximity status flag in an active state when the average value exceeds a predetermined threshold, wherein the capacitive proximity sensor is configured to reduce a power of the radio transmitter in response to the active state of the time-averaged proximity status flag, the averaging unit comprising an input logic gate configured to inhibit supplying of the values of the digital variable to the FIFO buffer when the average value exceeds the predetermined threshold.