| 摘要 |
PROBLEM TO BE SOLVED: To provide a waveform shaping circuit, etc., which shapes an input signal into a waveform of 50% duty and outputs it regardless of whether it is 50% duty. SOLUTION: A duty deciding circuit which receives a timing signal produced by a timing generation circuit 2 and decides and indicates a timing position of 50% duty of a clock signal to be outputted is provided, it consists of a cycle measuring circuit 10, which measures the length of each N cycle that arrives at every integral multiple interval of the N cycles of an input clock signal CK, an arithmetic circuit 19 which calculates the half length of the N cycle based on the value, a measuring circuit 20 which executes the measurement of the length in each cycle in the interval and a coincidence circuit 28 which outputs a coincidence signal as the timing position of the 50% duty, when the measurement value coincides with the calculated value, produces a clock signal that has pulse width corresponding to the 50% duty, based on a signal that synchronizes with the front end of the signal CK and the timing position which is decided and instructed by the duty deciding circuit 3 and outputs it. |
