A Low Power Continuous-Time Zoom ADC for Audio Applications

Abstract

This paper presents a continuous-time (CT) zoom ADC for use in audio applications. Compared to previous zoom ADCs, its input impedance is mainly resistive, making it much easier to drive while still maintaining high energy efficiency. The prototype is fabricated in a 0.16 pm CMOS process, occupies 0.27 mm2 and achieves 108.5 dB DR, 108.1 dB SNR, 106.4 dB SNDR in a 20 kHz BW, while consuming 618 pW. This results in a state-of-the-art Schreier FoM of 183.6 dB.

A 440μW, 109.8dB DR, 106.5dB SNDR Discrete-Time Zoom ADC with a 20kHz BW

“…Table I summarizes the performance of the zoom ADC and compares its performance to that of other state-of-the-art audio ADCs and previous zoom ADCs. Compared with a recent zoom ADC [5], its energy efficiency (FoM S ) is nearly 3 dB better even though its OSR is 30% lower. Compared with a recent DT zoom ADC [4], this design achieves similar energy efficiency and area while achieving 20× more BW.…”

“…20, the ADC's noise floor remains stable in the presence of −1.5-dB FS interferers at frequencies <80 kHz. Compared with a previous zoom ADC [5], this represents a 2× improvement in interferer robustness and is mainly due to the use of a 2-bit M. Fig. 21 shows the SNR and SNDR for −1.5-dB FS input signals at 1 kHz for 25 different samples.…”

3.6 A CMOS Resistor-Based Temperature Sensor with a 10fJ·K2 Resolution FoM and 0.4°C (30) Inaccuracy From −55°C to 125°C After a 1-point Trim

“…3.6.3). As in [6], it is biased via Rb and capacitively-coupled to the WhB via Cb. Chopping enables the amplification of the bridge's DC output signal, and also suppresses the OTA's offset, even-order distortion and 1/f noise.…”

“…6.6 summarises the performance of the proposed FIR-DAC WhB sensor and compares it with state-of-the-art BJT[1], resistor…”

A 440-μW, 109.8-dB DR, 106.5-dB SNDR Discrete-Time Zoom ADC With a 20-kHz BW

“…INTRODUCTIONA UDIO applications often require analog-to-digital converters (ADCs) with high dynamic range (DR), high energy efficiency, and low area [1]-[3]. By combining a lowpower successive-approximation register (SAR) ADC with a high-resolution delta-sigma modulator (M), zoom ADCs can meet all these requirements [4], [5]. The SAR ADC determines the coarse references of the fine M, drastically reducing loop filter swing and enabling energy-efficient design.…”