Method and apparatus for measuring the duty cycle or relative duty cycle of a digital signal

[Subject] A method and a device which measure a duty cycle or a relative duty cycle of a digital signal are provided. [Means for Solution] A method and a device which were indicated measure a duty cycle of a clock signal. A variable duty cycle circuit receives a clock signal from a clock signal generator. As for a variable duty cycle circuit, only quantity depending on a duty cycle-index value which it receives adjusts a duty cycle of a clock signal. A variable duty cycle circuit supplies a clock signal with which a duty cycle was adjusted to a part circumference way. The sweep of this device is carried out to the maximum frequency in which a part circumference way fails frequency of a clock signal in more than it from an initial value. Next, this device determines a duty cycle of a clock signal with which a duty cycle was adjusted from the maximum frequency. In one embodiment, a method and a device which were indicated measure relative duty cycle information on a clock signal on an input node at the time of a clock signal progressing to a node as which a clock distribution network on an electronic circuit was chosen. [Chosen drawing] Drawing 5