EXPONENTIAL FIT TEST - THEORETICAL ANALYSIS AND PRACTICALLY IMPLEMENTATION

Josef Vedral

Abstract

ADC testing by means of exponential signal is presented in the article. Time and frequency analysis of the signal is performed and Signal-to-Noise Ratio and Effective Number of Bits is calculated by means of Exponential Fit Test. The approach has been verified on 24-bit Flexible Resolution Digitizer PXI-5922 by National Instruments. Using exponential signal as the digitizer input, the SINAD = 106 dB corresponding to ENOB = 17,3 bits has been achieved. The difference of 1,5 bit was most probably caused by exponential signal frequency spectra decrease. Results comparable with classical sine-fit method indicate the possibility of consideration of the proposed method as an alternative digitizer test method. Achieved results prove the method applicability for dynamic testing of up to 16 bit digitizers, and method simplicity allows for embedded applications. The frequency spectra can be easily modified by changing the time constant of RC element.

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IMEKO-IWADC-2008-005.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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