High-Precision Evaluation System Using High-Order Digital Δ∑ Modulator for Digital Audio System

In digital audio systems, ΔΣ modulation has widely been adopted in a digital-to-analog converter (DAC) for Class-D amplifiers and an analog-to-digital converter (ADC). To evaluate the ΔΣ modulator, in most cases, a high-performance analog signal generator and several costly band-pass filters are necessary. Hence, a low-cost evaluation system using the 1-bit stream is proposed [1]; nonetheless, in this system, the measurement precision is insufficient, and dispersion occurs in the evaluation result. This paper presents a high-precision evaluation system that enables ΔΣ modulator measurement with repeatability.