| 摘要 |
PURPOSE: A clock generator using a ring oscillator is provided which performs accurate phase control using a direct digital synthesis technique and carries out pulse triggering with a frequency generated by a ring oscillator using a delay cell to generate a precise variable clock. CONSTITUTION: A clock generator includes a phase accumulator(300) for accumulating a phase increment in synchronization with a reference clock, a phase shift detector(400) for generating a trigger enable signal when the accumulated phase is shifted, a trigger position generator(500) for obtaining a trigger distance(TD) to a point where phase shift occurs when the phase shift is generated, and a pulse trigger part(600). The pulse trigger part detects a right count value at a predetermined edge of the reference clock using tap signals generated by an inner ring oscillator and a phase count value obtained by counting one of the tap signals, and generates a resolution that indicates how many triggers can be created in one section of the reference clock from the ring count value. In addition, the pulse trigger part operates the resolution, trigger distance and phase increment to convert the trigger distance into a ring count unit and generates a pulse at a position where the ring count unit is added to a predetermined offset value.
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