Adaptive Signal to Noise Ratio Scalable Analog Front-End Continuous Time Sigma Delta Converter For Digital Hearing Aids.

摘要

A dual-channel directional digital hearing aid (DHA) front end using Micro Electro Mechanical System (MEMS) microphones and an adaptive-power analog processing signal chain is presented. The analog front end consists of a double differential amplifier (DDA) based capacitance to voltage conversion circuit, 40dB variable gain amplifier (VGA) and a continuous time sigma delta analog to digital converter (CT - SigmaDelta ADC). Adaptive power scaling of the 4th order CT - SigmaDelta achieves 68dB SNR at 120muW, which can be scaled down to 61dB SNR at 67muW. This power saving will increase the battery life of the DHA.