Abstract: A high-speed digitally voltage controlled oscillator with 1/N phase resolution, having a load counter, 1/N phase difference generator, a multiplexor, a clock selector, and a load controller. The high-speed digitally voltage controlled oscillator only needs a load counter with an input frequency D+1 (D is far smaller than N) times an output frequency thereof. The phases of first and (M/2+1)th phases of M clock signals with 1/N phase difference (M is far smaller than N) generated by the 1/N phase difference generator are fixed at 0° and 180° with respect to a reference clock. Therefore, only (M/2−1) clock signals are affected by variation of process parameters. Consequently, the high-speed digitally voltage controlled oscillator can tolerate variation error of process parameter and is applicable for high resolution and high frequency operation.