An ultra-low power analogue directionality system for digital hearing aids

An ultra-low power analogue system used to provide adaptive directionality in hearing aids is proposed. A digital algorithm converter to analogue is shown to be considerably more power efficient. Power reduction is obtained by designing all the circuit blocks in a CMOS technology using transistors in weak inversion. The system performs comparably to a digital equivalent in terms of the algorithm but with a total power consumption of 5 μW at a power supply voltage of 900 mV.