Analog-to-digital conversion beyond 20 bits

Abstract

Analog-to-digital converters with resolution exceeding 20 bits are widely available today. They exist in two forms-flexible laboratory instruments and monolithic integrated circuits. We present an overview of application fields for such digitizers, the hardware architectures that implement them, and their limitations. We review the state of the art by comparing the best-performing devices reported in scientific literature, as well as those available commercially. Our focus is particularly on integrated circuit solutions, and among our aims are the disambiguation of the multiple performance metrics in use, as well as the presentation of a clear perspective on basic performance tradeoffs. Finally, we provide a discussion on the future prospects for highresolution digitizing measurement systems.

Design and Metrological Characterization of a Digitizer for the Highest Precision Magnet Powering in the High Luminosity Large Hadron Collider

“…The digitizer is built around an integrated Sigma-Delta ADC-the AD7177-2 by Analog Devices. It was selected following a market study of high-resolution ADCs [10] and subsequent laboratory tests on selected candidates. The AD7177-2 was found to have the lowest intrinsic 1/ f noise of all tested devices, in particular when its built-in buffers are disabled.…”

“…11. The figure demonstrates directly the performance metric known as "peak-to-peak resolution," "noise-free bits," or "noise-free code resolution" [10]. At 1 Sample/s this metric exceeds 23 bits referred to 10 V (level spacing of 1.192 µV, thus 1/2 LSB = 596 nV) or 24 bits of the bipolar 20 V range, not taking into account the additional over-range margin.…”

Easy as piadcs: A low‐cost, ultra‐high‐resolution data acquisition system using a Raspberry Pi

“…Although the ADC used in this system has a nominal resolution of 32-bits, the actual system precision is lower, especially as the data rate increases. Noise remaining in the system (e.g., thermal noise), along with the inherent tradeoff between ADC speed and resolution, causes the effective resolution of an ADC to be lower than its nominal resolution (Beev, 2018). The noise floor and, therefore, the effective resolution of our system is very close to that specified in the ADS1262 datasheet for the data rates and digital filters tested (Table 2), and is a major improvement over other existing open-source DAQ systems for the Raspberry Pi.…”

“…A few important specifications to consider when choosing an ADC are bit resolution, sampling rate, and number of channels. There is a necessary tradeoff between an ADC's sampling rate and effective resolution, in that ADCs with very high resolutions are limited to sampling rates in the kilohertz range or less and that as the sampling rate of a given ADC is increased the effective resolution declines (Beev, 2018). For applications where ultra‐high‐resolution is not critical, there are many ADCs on the market that have readily available open‐source software libraries and schematics for interfacing with a Raspberry Pi.…”

Impact of the Noise on the Emulated Grid Voltage Signal in Hardware-in-the-Loop Used in Power Converters

“…Furthermore, the predominance of one type of noise or another in the ADC depends on its resolution; thus, in a low-resolution ADC, quantization errors will predominate, while in a high-resolution ADC, thermal noise will predominate. In this sense, the ADC is not trivial [31,32]. Different types of ADC can be used in building a HIL.…”