A 101 dB Dynamic Range Delta-Sigma Modulator Using Modified Feed-Forward Architecture for Audio Application

Abstract

This paper presents a second-order delta-sigma modulator for audio applications. It uses modified feed-forward (FF) architecture that simplifies the switched-capacitor network of an analog adder in front of the quantizer. The modulator utilizes correlated-double-sampling (CDS) technique to attenuate flicker noise of the op-amp in the first integrator. The prototype analog-to-digital converter (ADC) is fabricated in a 0.18 µm CMOS process with an active die area of 0.119 mm2. It achieves a dynamic range (DR) of 101dB, a peak signal-to-noise ratio (SNR) of 97.7 dB and a peak signal-to-noise and distortion ratio (SNDR) of 91.5 dB in a 24kHz signal bandwidth while consuming 1.55 mW from a 1.8 V power supply.