An analog VLSI low-power envelope periodicity detector

The low-power, low-cost detection of voices or engine rumble is a desirable function in many different applications. Typical approaches involving frequency-domain computation are quite computationally intensive and require a significant power budget. In an effort to construct a very low-power detector capable of acting as a wake-up signal for other systems, we have designed a low-power (less than 1.8-/spl mu/W) subthreshold analog very large-scale integration circuit that detects periodicity in the time-domain envelope of the acoustic signal. The circuit was fabricated in a commercially available 2-poly 1.5-/spl mu/m CMOS process and occupies an area of about 0.242 mm/sup 2/.