Design and analysis of logarithmic digital quantizers with applications to low-power data interfaces for speech processing

raditionally, digital voice-band systems have employed either uniform, ;Moreover, it is shown that this approach results in performance quite similar to that exhibited by traditional compandors. Quantization noise characteristics for the case of a finite word length are derived. Also, the effects upon system performance when input signals possess a non-zero mean are presented. Performance degradation due to harmonic distortion, introduced by mismatches in the logarithm base among different subsystems, are quantified. Simple, power-efficient converters are then proposed based upon the switched-capacitor equivalent of a parallel RC network and factoring of the digital data. The effects of nonidealities in the active and passive components on coder performance are also established.;In order to demonstrate the usefulness of the proposed encoder-decoder, the design of an experimental Analog Interface Processor (AIP) for use in a Digital Hearing Aid (DHA) is described. This experimental prototype includes, in addition to the data conversion circuits, an anti-aliasing filter, a low-noise preamplifier, and several spectral shaping circuits. Finally, experimental data obtained from circuits fabricated in a standard 2...