A high-performance, low-power σ Δ ADC for digital audio applications

Abstract

A high-performance low-power † analog-to-digital converter (ADC) for digital audio applications is described. It consists of a 2-1 cascaded † modulator and a decimation filter. Various design optimizations are implemented in the system design, circuit implementation and layout design, including a high-overload-level coefficientoptimized modulator architecture, a power-efficient class A/AB operational transconductance amplifier, as well as a multi-stage decimation filter conserving area and power consumption. The ADC is implemented in the SMIC 0.18-m CMOS mixed-signal process. The experimental chip achieves a peak signal-to-noise-plus-distortion ratio of 90 dB and a dynamic range of 94 dB over 22.05-kHz audio band and occupies 2.1 mm 2 , which dissipates only 2.1 mA quiescent current in the analog circuits.

A fourth-order bandwidth-reconfigurable delta—sigma modulator for audio applications

“…3, using a large PMOS input pair to suppress flicker noise for the first stage and a class AB second stage, as can be seen in Ref. [7]. A compensation capacitor (C c / is bridged between the two stages to split two poles, while a series resistor (R c / is inserted to avoid a right half-plane zero.…”