Micropower mixed-signal acoustic localizer

A micropower VLSI system-on-chip is presented for 3-D localization of a broadband acoustic source. The direction of the source is estimated by relating spatial and temporal differentials of acoustic signals acquired over a planar geometry of four microphones. Two stages of mixed-signal least-squares adaptation perform common-mode rejection for increased sensitivity in the analog differentials, and directly produce digital estimates of the direction cosines. The 3 mm × 3 mm chip in 0.5 μm CMOS technology quantizes signal delays with 2 μs resolution at 2 kHz sampling rate and at 32 μW power dissipation.