Analogue VLSI implementations of two dimensional, nonlinear, active cochlea models

This paper presents results from integrated circuit (IC) implementations of the active, nonlinear, two dimensional (2D) silicon cochlea. It begins by developing an active, 2D cochlea model which is based on the idea that the cochlear amplifier (CA) has dynamics governed by the Hopf equation. The realisation of the active 2D model leads to several hardware implementations that are based on two slightly different but equivalent approaches. The first implementation is called automatic quality factor control (AQC) which has the dynamics of a system that is governed by the Hopf equation and represents a type of parametric amplification. The second approach is based on implicitly modelling the Hopf equation as a Hopf oscillator. Together this work provides the foundations for a silicon cochlea that can be used to better understand the biological cochlea as well as explore higher auditory centres.