Inductive Sensing: A Phase Detector IC for Button Replacement in Mobile Devices

This paper describes a 4-channel phase detector based inductive sensing IC targeted at mobile device mechanical button replacement. Salient features include active-drive TX with low EMI sensitivity (<10mV differential drive), interference robustness and scalable performance. First silicon achieves an industry leading combination of performance (0.1μm displacement sensitivity) and power (124μW @100 Hz scan rate). Keywords— Sensors, Inductive Sensing, Resonant Phase Sensing, Mechanical/Virtual Buttons, I/Q Demodulation.