A 260µW infrared gesture recognition system-on-chip for smart devices

This paper presents a low-power infrared motion detection system suitable for smart devices such as wearables. The SoC incorporates instrumentation chopper amplifiers (ICA), LPFs, ADCs, and a DSP. The low-noise ICAs amplify very low frequency μV-level thermopile outputs with 2.0 NEF and provide programmable gain modes. To reduce standby power the ICA uses lower current when the system is in idle mode. Wakeup can be triggered by detection of a simple gesture. For the LPF, source degeneration by pseudo-resistors and gm division techniques are used for both improved linearity and 30Hz bandwidth. The DSP employs a motion history image technique to achieve low-power detection. The system consumes 260μW in active mode and 46μW in idle mode while processing 16×4 infrared data at 30fps. A complete system demonstration is shown.