A Single-Chip Stereo Audio Delta-Sigma A/D Converter with 117 dB Dynamic Range

A 24-bit, 96 kHz stereo A/D converter (ADC) for DVD-audio has been developed. The single-chip integrates stereo delta-sigma modulators (∆ΣM’s), a voltage reference, and a decimation filter. A fourth-order cascaded ∆ΣM using a local feedback technique was employed to avoid overload without sacrificing noise performance. Low power switched-capacitor techniques were used for implementation. A two-stage decimation filter architecture that reduces digital switching noise was also developed. A merged multi-stage comb filter was used for the first stage, and a bit-serial finite-impulse-response (FIR) filter was used for the second stage. The 18.0mm2 chip was fabricated in 0.6-μm CMOS with low threshold devices. Measured results show 117 dB A-weighted dynamic range in the 20 kHz passband, with 470mW power dissipation at 5V operation. key words: A/D converter, delta-sigma modulator, switchedcapacitor circuits, digital filter