A Review of Sub- μ W CMOS Analog Computing Circuits for Instant 1-Dimensional Audio Signal Processing in Always-On Edge Devices

Reducing the power consumption of intelligence edge devices that require long standby periods is highly significant. The use of CMOS analog computing circuits for instant feature extraction and wake-up signal generation from the sensed signal has emerged as an efficient signal processing paradigm for data volume reduction and power minimization. This review highlights the progress of ultra-low-power (sub- $\mu $ W) analog computing circuits for instant 1-dimensional audio signal processing in edge devices in recent years, at architecture and circuit levels. A comparative analysis of existing works is presented, offering choices that cater to various performance requirements. The low power consumption in the range of tens of nanowatts has been achieved. Finally, we provide insights into the future potential of these analog computing circuits.