| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency measurement circuit which measures the period or the frequency of a clock to be measured with high accuracy. <P>SOLUTION: The frequency measurement circuit includes a counter which counts edges to be measured of the clock to be measured; a counter latch circuit which stores a count value of the counter in response to a reference edge of a reference clock; a delay circuit which has a plurality of basic delay circuits D(1)-D(m) connected in series, and inputs the clock to be measured in a basic delay circuit at the initial stage to be propagated; an edge detection circuit which detects the position of the edge to be measured in the delay circuit, on the basis of output of the plurality of basic delay circuits latched by the delay latch circuits; and a computing unit which calculates the period or frequency of the clock to be measured from the counted value between two reference edges and positional information of the edges to be measured to be detected by a first edge detection circuit at the two reference edges. <P>COPYRIGHT: (C)2011,JPO&INPIT |
