A Bio-Realistic Analog CMOS Cochlea Filter With High Tunability and Ultra-Steep Roll-Off

IEEE Trans Biomed Circuits Syst. 2015 Jun;9(3):297-311. doi: 10.1109/TBCAS.2014.2328321. Epub 2014 Jul 31.

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 20 dB, 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 9th 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cochlea / physiology*
  • Electronics, Medical / instrumentation*
  • Equipment Design / methods
  • Humans
  • Signal Processing, Computer-Assisted / instrumentation*