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Analog-to-digital converters (ADCs) are needed in all those applications which, interfacing with the analogue world, exploit the digital processing of data. As digital processing is more and more gaining ground over analogue signal processing, the importance of ADCs correspondingly increase.
Digital signal processing systems are generally designed by considering analogue-to-digital converters (ADC's) as ideal components affected only by quantization and sampling errors. Viceversa, the effect of the ADC actual working conditions modifies the expected digital values and could compromise the effectiveness of the digital signal processing as a whole. ADC's are among the components that mostly influence metrological performance of digital measurement systems. ADC errors limit system dynamic, its frequency band and so on, by adding distortion and error effects to the output. Therefore, a deeper insight into the ADC characteristics is needed.
Furthermore, the digital-to-analogue converters (DACs) are widely used in many fields, i.e. in the automatic system to drive actuators, in the digital music, and so on. In particular, the possibility to integrate in one chip an ADC, a DAC and a DSP has improved the applicability of these components to new fields, as in mobile telecommunication systems.
In order to improve the ADC and DAC performance many efforts are now carrying out in several Research Centres. The efforts are oriented to set up new models, testing methods and error correction techniques.
As in other technical fields, also in the ADC error investigation the use of models has become more and more widespread. Modelling actual ADC allows the error characteristic to be analysed and, hence, its correction to be carried out more easily. Then, in the diagnostic process, it allows a fault model to be set up in order to isolate a possible fault condition.
In order to improve the ADCs and DACs performance, some ideas have been proposed, either linked to the improvement of the chip design or related to the correction of the ADC and DAC errors by means of correction techniques. This last field requires to set up opportune models and testing techniques to correctly estimate the metrological characteristics of the corrected component.
These problems are of high relevance not only for producers but mainly for system integrators and end-users. Such customers build complex systems where the accuracy of ADC and DAC impacts in a decisive way the property of final product. Consequently user-friendly standards for ADC and DAC assessment will be highly welcome for these target users. It is worth to underlying that; now, there is a lack in the realisation of a European standard for ADCs and DACs.
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