9.2 a 134µw 24khz-bw 103.5db-dr ct ΔΣ modulator with chopped negative-r and tri-level fir dac

IEEE J. Solid-State Circuits

Gönen³

et al. 2021

This article describes a discrete-time zoom analogto-digital converter (ADC) intended for audio applications. It uses a coarse 5-bit SAR ADC in tandem with a fine third-order delta-sigma modulator (M) to efficiently obtain a high dynamic range. To minimize its over-sampling ratio (OSR) and, thus, its digital power consumption, the modulator employs a 2-bit quantizer and a loop filter notch. In addition, an extra feed-forward path minimizes the leakage of the SAR ADC's quantization noise into the audio band. The prototype ADC occupies 0.27 mm 2 in a 0.16-μm technology. It achieves 109.8-dB DR, 106.5-dB SNDR, and 107.5-dB SNR in a 20-kHz bandwidth while dissipating 440 μW. It also achieves state-of-the-art energy efficiency, as demonstrated by a Schreier FoM of 186.4 dB and an SNDR FoM of 183.6 dB. Index Terms-A/D conversion, asynchronous SAR analogto-digital converter (ADC), audio ADC, delta-sigma ADC, discrete-time (DT) delta-sigma, dynamic zoom ADC, inverter-based operational transconductance amplifier (OTA), low-power circuits, multi-bit quantizer. I. 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. The overall digital output is then obtained by simply summing the outputs of both converters.Recently proposed Ms with finite impulse response (FIR) DACs and negative-R-assisted integrators are also capable of satisfying the requirements of audio applications [2], [3], [6], [7]. An FIR DAC essentially filters out the fed back quantization noise and, thereby, also relaxes

Section: Measurement Resultsmentioning

confidence: 96%

Section: Out-of-band Interferersmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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

IEEE J. Solid-State Circuits

Gönen³

et al. 2021

“…Compared with a recent DT zoom ADC [4], this design achieves similar energy efficiency and area while achieving 20× more BW. Although the FoM S of the negative-R CT M in [3] is nearly the same, this work achieves 7 dB more SNDR and occupies about the same area in an older technology node. To summarize, compared with the other audio ADCs, this design uses one of the lowest sampling frequencies to achieve the highest energy efficiency and the highest DR.…”

Section: Measurement Resultsmentioning

confidence: 96%

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

2020 IEEE Symposium on VLSI Circuits

Gönen

et al. 2020

This article describes a discrete-time zoom analogto-digital converter (ADC) intended for audio applications. It uses a coarse 5-bit SAR ADC in tandem with a fine third-order delta-sigma modulator (M) to efficiently obtain a high dynamic range. To minimize its over-sampling ratio (OSR) and, thus, its digital power consumption, the modulator employs a 2-bit quantizer and a loop filter notch. In addition, an extra feed-forward path minimizes the leakage of the SAR ADC's quantization noise into the audio band. The prototype ADC occupies 0.27 mm 2 in a 0.16-μm technology. It achieves 109.8-dB DR, 106.5-dB SNDR, and 107.5-dB SNR in a 20-kHz bandwidth while dissipating 440 μW. It also achieves state-of-the-art energy efficiency, as demonstrated by a Schreier FoM of 186.4 dB and an SNDR FoM of 183.6 dB. Index Terms-A/D conversion, asynchronous SAR analogto-digital converter (ADC), audio ADC, delta-sigma ADC, discrete-time (DT) delta-sigma, dynamic zoom ADC, inverter-based operational transconductance amplifier (OTA), low-power circuits, multi-bit quantizer. I. INTRODUCTION A 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. The overall digital output is then obtained by simply summing the outputs of both converters. Recently proposed Ms with finite impulse response (FIR) DACs and negative-R-assisted integrators are also capable of satisfying the requirements of audio applications [2], [3], [6], [7]. An FIR DAC essentially filters out the fed back quantization noise and, thereby, also relaxes

A 590 µW, 106.6 dB SNDR, 24 kHz BW Continuous-Time Zoom ADC with a Noise-Shaping 4-bit SAR ADC

Mehrotra

ESSCIRC 2022- IEEE 48th European Solid State Circuits Conference (ESSCIRC)

et al. 2022

This paper presents a continuous-time zoom ADC for audio applications. It combines a 4-bit noise-shaping coarse SAR ADC and a fine delta-sigma modulator with a tail-resistor linearized OTA for improved linearity, energy efficiency, and handling of out-of-band interferers compared to previous designs. In 160 nm CMOS, the prototype chip occupies 0.36 mm 2 , achieves 107.2 dB SNR, 106.6 dB SNDR, and 107.3 dB dynamic range in a 24 kHz bandwidth while consuming 590 µW from a 1.8 V supply. This translates into a Schreier figure-ofmerit (FoMS) of 183.4 dB and a FoMSNDR of 182.7 dB. Keywords-A/D conversion, audio analog to digital converter (ADC), continuous-time delta-sigma ADC, dynamic zoom ADC, low-power circuits, noise-shaping SAR ADC, high linearity operational transconductance amplifier (OTA)