0.04-mm 2 103-dB-A Dynamic Range Second-Order VCO-Based Audio $\Sigma\Delta$ ADC in 0.13- $\mu$ m CMOS

This paper presents a compact-area, low-power, highly digital analog-to-digital converter (ADC) for audio applications. The proposed converter is implemented using only oscillators and digital circuitry, without operational amplifiers nor other highly linear circuits. The ADC consists of two twin second-order $\Sigma \Delta $ modulators, which can work both individually or in a pseudodifferential configuration. The proposed system has been implemented in a 0.13- $\mu \text{m}$ standard CMOS technology. The single-ended configuration occupies an active area of 0.02 mm 2 , is powered at 1.8 V with a current consumption of 155 $\mu \text{A}$ , and achieves an A-weighted dynamic range (DR) of 98 dB-A. The pseudodifferential configuration achieves 103 dB-A of A-weighted DR at the expense of doubling the area and power consumption.