Micro Power “relative Precision” 15-bit A/d Converter

State of the art A/D converters are still critical in power-sensitive, battery-operated equipment like hearing aids. In this article, a new approach is presented that features excellent signal quality, 85 dB dynamic range equivalent to a 15-bit output word, 16 kHz sampling rate, 25 μW power consumption, and 0.54 mm2 chip area. Compared to standard components, the enormous power savings result from a sophisticated circuit design which limits the signal to quantization noise ratio to roughly 40 dB. Subjective listening tests prove, however, that the resulting signals are hardly distinguishable from their unprocessed versions, a remarkable fact due to masking effects inherent in the human auditory system.