| 摘要 |
PURPOSE:To evaluate simply the tendency of a converting characteristic by selecting the relation between a sinusoidal clock fs and a sampling clock fCLK fed to an A/D converter as fc=fCLK(1+1/n)/N (where N is an optional integer and n is a required sampling number), extracting an output code an interval of N and converting the code into a data string. CONSTITUTION:The sinusoidal wave fs and the sampling clock fCLK are inputted to an A/D converter 3 being an IC to be tested, the converted output code is sampled at an interval of N and stored in a buffer memory corresponding to beat frequency fCLK/(n N) between the fc and fCLK, then n-set of stored data string is a sinusoidal wave data for one period's share of the said beat frequency. The ideal sinusoidal wave closest to the beat frequency is calculated from the n-set of data strings by means of a DFT (discrete Fourier conversion) and a computer 5 evaluates the dynamic performance of the A/D converter from the difference between the ideal sinusoidal wave and the actual data.
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