A bio-realistic analog CMOS cochlea filter with high tunability and ultra-steep roll-off

Wang, Shiwei, Koickal, Thomas Jacob, Hamilton, Alister, Cheung, Rebecca and Smith, Leslie S. (2015) A bio-realistic analog CMOS cochlea filter with high tunability and ultra-steep roll-off. IEEE Transactions on Biomedical Circuits and Systems, 9 (3), 297-311, [6869048]. (doi:10.1109/TBCAS.2014.2328321).

Abstract

This paper presents the design and experimental results of a cochlea filter in analog very large scale integration (VLSI) which highly resembles physiologically measured response of the mammalian cochlea. The filter consists of three specialized sub-filter stages which respectively provide passive response in low frequencies, actively tunable response in mid-band frequencies and ultra-steep roll-off at transition frequencies from pass-band to stop-band. The sub-filters are implemented in balanced ladder topology using floating active inductors. Measured results from the fabricated chip show that wide range of mid-band tuning including gain tuning of over 20dB, Q factor tuning from 2 to 19 as well as the bio-realistic center frequency shift are achieved by adjusting only one circuit parameter. Besides, the filter has an ultra-steep roll-off reaching over 300 dB/dec. By changing biasing currents, the filter can be configured to operate with center frequencies from 31 Hz to 8 kHz. The filter is 9^th order, consumes 59.5∼ 90.0 μW power and occupies 0.9 mm² chip area. A parallel bank of the proposed filter can be used as the front-end in hearing prosthesis devices, speech processors as well as other bio-inspired auditory systems owing to its bio-realistic behavior, low power consumption and small size.

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Contributors

Author: Shiwei Wang

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