S? Modulator System-Level Considerations for Hearing-Aid Audio Class-D Output Stage Application

This paper deals with a system-level design of a digital sigma-delta (SigmaDelta) modulator for hearing-aid audio Class D output stage application. The aim of this paper is to provide a thorough discussion on various possibilities and tradeoffs of ???? modulator system-level design parameter combinations - order, oversampling ratio (OSR) and number of bits in the quantizer - including their impact on interpolation filter design as well. The system is kept in digital domain up to the input of the Class D power stage including the digital pulse width modulation (DPWM) block. Notes on the impact of the DPWM block on the modulated spectrum are provided. Keywords-Sigma-Delta modulator; Interpolation filter; Class D; Hearing aid; low voltage, low power