FREQUENCY SPECTRUM CORRECTION TEST – PRACTICAL EXPERIENCE

Vladimir Haasz, David Slepicka

Abstract

The main problem of the high resolution ADC testing within the frequency range hundreds of kHz to several MHz is the spectral purity of a testing signal. Commercially produced low-distortion generators have the spectral purity sufficient for testing of 16 bits ADCs only up to frequencies of tens of kHz; at higher frequencies the spectral purity of generators is generally worse. Some improvement can bring signal filtering. However, most of the LC filters use coils with ferromagnetic cores for the frequency range up to several hundreds of kHz, which can cause a rise of odd harmonic components. Nevertheless, these components can be measured and subtracted from the spectrum calculated from ADC output data. In the ideal case, only the frequency spectrum corresponding to the ADC non-linearity remains. An ADC measurement system was designed and built for the verification of this method in the frequency range 200 kHz to 1 MHz. The practical experience of its application is described in this paper.

Keywords

ADC testing, frequency spectrum correction, phase spectrum, FFT

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IMEKO-IWADC-2004-012.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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