| 摘要 |
PURPOSE:To evaluate simply a conversion error at a high speed by providing a special relation between an input signal frequency fs and a sampling clock frequency fCLK, interleaving an output code of an A/D converter to be tested at an interval of (N-1) codes and comparing two consecutive data strings obtained in this way. CONSTITUTION:The relation of fs=(fCLK/N)+DELTAf (N:1,2,3 and fs>>DELTAf) is held between a sampling clock frequency fCLK and a frequency fs of a continuous period function wave inputted to an A/D converter 3 to be tested, the output codes obtained by the conversion of the A/D converter 3 are interleaved at an interval of (N-1) codes and two consecutive data strings obtained are inputted to a subtractor 7. An error discriminator 8 detects the conversion error by observing the difference of the two conswecutive data from the subtractor 7. The data string being the result of interleaving the output codes at an interval of (N-1) codes becomes a frequency function wave data by one period with a number of fCLK/NDELTAf and beat frequency DELTAf. The value DELTAf is selected so that the difference of two consecutive data at the maximum gradient of the periodic function wave is sufficiently smaller than the allowable calculated conversion error.
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