The CapSense design in portable media players

The adoption of capacitive sensing as an interface technology in portable media players and mobile handsets has created demand for the same technology in more conventional consumer electronics. Demand has led to significant innovation and several competitive technologies are available. While these technologies each have their respective differences, the underlying principle is the measurement of capacitance between a plate (the sensor) and its environment. Sensing techniques can employ ADCs, comparators, and switching mechanisms. In the case of limited number on sense, the demand with high resolution & credible sensitivity is choke point in technology. The 2-levels filter arithmetic is put forward in the paper, which is applied to reduce great the noise on sense channel. It is always stable, and offer higher performance for the case of limited number on sense.