| 摘要 |
A duty discriminating circuit for discriminating a duty of an information signal whose level varies periodically on the basis of a threshold value, has a counter circuit (12) for detecting a time period of a precedent portion of the information signal by counting the number of reference clock signals; a shift circuit (14) for shifting the precedent portion time data obtained by the counter circuit; a discriminating circuit (15) for obtaining a discriminate point by comparing a time period of a subsequent portion of the information signal with a virtual threshold value corresponding to the time data shifted by the shift circuit; and an output circuit (16,17) for outputting a duty discriminate signal on the basis of relationship between the discriminate point outputted by the discriminating circuit and the subsequent portion time data. <IMAGE> |
