A 15nW per Button Noise-Immune Readout IC for Capacitive Touch Sensor
Said Hussaini (Student TU Delft)
Hui Jiang (TU Delft - Electronic Instrumentation)
Paul Walsh (Cypress Semiconductor, Cork)
Dermot MacSweeney (Cypress Semiconductor, Cork)
Kofi A.A. Makinwa (TU Delft - Microelectronics)
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Abstract
This paper presents a readout IC that uses an asynchronous charge-redistribution-based capacitance-to-digital-converter (CDC) to digitize the capacitance of a touch sensor. Thanks to the power efficient tracking algorithm, the CDC consumes negligible power consumption in the absence of touch events. To facilitate stand-alone or wake-on-touch applications, the CDC can be periodically triggered by a co-integrated ultra-low power relaxation oscillator. At a 38 Hz scan-rate, the readout IC consumes 15 nW per touch sensor, which is the lowest reported to date.