FLEXIBLE ADC: A DITHER AND OVERSAMPLING BASED SOLUTION TO IMPROVE THE PERFORMANCE OF ADC SYSTEMS

J. M. Dias Pereira, A. Cruz Serra, P. Girão

Abstract

A well-known technique that can be used to increase the resolution of ADC digitising systems is based on dithering, oversampling and noise shaping. Dithering assures a uniform power spectral density for the quantisation error, oversampling. Followed by digital filtering, it improves signal to noise ratio and effective number of bits at the expenses of the input signal bandwidth. Noise shaping removes quantisation error power from signal bandwidth. The present paper introduces the concept of a flexible ADC that can be applied to an ordinary data acquisition board as a solution to optimise digitising systems performance for different sampling rates. Gains of ten or more effective bits can be obtained, for low frequency input signals, using always the maximum sampling rate of the ADC together with dithering, oversampling and noise shaping techniques.

Keywords

dither, oversampling, noise shaping

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IMEKO-WC-2000-EWADC-P612.pdf

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