Fast estimation of ADC nonlinearities using the Sinewave Histogram Test
ABSTRACT The Sinewave Histogram Test (SHT) is a widely used standard technique to estimate the threshold voltages and the Integral NonLinearity (INL) pattern of Analog-to-Digital Converters (ADCs). The main drawback of the SHT is that, for a given target accuracy, the number of test samples as well as the testing time tend to increase exponentially as the resolution of the converter grows. The strategy described in this paper still relies on the SHT, but it enables a major reduction in testing time without affecting estimator accuracy provided that the INL pattern exhibits prevailingly a low code frequency content. This result can be achieved simply by suitably filtering the INL pattern obtained using a standard SHT over a reduced amount of test samples. After being justified theoretically, the proposed solution is validated by means of both simulations and experimental evidences.
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ABSTRACT: The increasing diffusion of mobile and portable de-vices provided with wireless connectivity makes the problem of distance measurement based on radio-frequency technologies in-creasingly important for the development of next-generation no-madic applications. In this paper, the performance limitations of two classic wireless ranging techniques based on received signal strength (RSS) and two-way time-of-flight (ToF) measurements, respectively, are analyzed and compared in detail. On the basis of this study, a data fusion algorithm is proposed to combine both techniques in order to improve ranging accuracy. The algorithm has been implemented and tested on the field using a dedicated embedded prototype made with commercial off-the-shelf compo-nents. Several experimental results prove that the combination of both techniques can significantly reduce measurement uncer-tainty. The results obtained with the developed prototype are not accurate enough for fine-grained position tracking in Ambient Assisted Living applications. However, the platform can be suc-cessfully used for reliable indoor zoning, e.g., for omnidirectional and adjustable hazard proximity detection. Most importantly, the proposed solution is absolutely general, and it is quite simple and light from the computational point of view. Accuracy could be further improved by using a more isotropic antenna and by integrating the ToF measurement technique at the lowest possible level on the same radio chip used for communication. Usually, this feature is not available in typical low-cost short-range wireless modules, e.g., for wireless sensor networks. Thus, the results of this research suggest that combining RSS with ToF measurements could be a viable solution for chip manufacturers interested in adding ranging capabilities to their radio modules.IEEE Transactions on Instrumentation and Measurement 01/2013; 62(1):27-37. DOI:10.1109/TIM.2012.2209918 · 1.71 Impact Factor
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ABSTRACT: Effects of error in code transition levels on nonlinearity and effective number of bits (ENOB) of an analog to digital converter (ADC) are presented in this article. Error in code transition level is determined by deviation of code transition levels from the mean of the estimated code transition levels. Errors in estimate of differential nonlinearity (DNL), integral nonlinearity (INL) and ENOB are computed by considering error in code transition levels and computing corresponding values. In this study, 5- and 8-bit ADC transfer characteristics are simulated and arbitrary nonlinearity errors are introduced. Suitable corrections are applied in code transition levels and computation of estimate of nonlinearity with and without corrections are reported. Results have been compared with earlier published work and improvements are observed. Effects of overdrive and additive noise on ENOB for 5-bit ADC are also reported.International Journal of Electronics 11/2011; 98(11-11):1503-1515. DOI:10.1080/00207217.2011.601440 · 0.75 Impact Factor