Abstract: Based on the problem that reference spurs and fractional spurs in fractional phase-locked loop are difficult to be eradicated, a technique of loop current pulses sampling is proposed for low spurs. By using a variable amplitude charge pump and a fixed-position variable-period pulse generator, loop current pulses were shaped to not only have fixed position, variable amplitude, but also have variable period. The properties of fixed position and variable amplitude of loop current pulses were used to eradicate reference spurs. And, the property of variable period of loop current pulses was used to reduce fractional spurs. The spur performance of a fractional phase-locked loop is analyzed by Spectre^TM when reference frequency is 20 MHz and division ratios are 120.13 and 120.25. Simulation results showed that loop tuned voltage has no reference spur at reference frequency of 20 MHz and its integer multiple frequencies, and the fractional spurs at fractional frequency of 10 MHz are 19.67 dB and 21.77 dB less than the existing techniques. Moreover, fractional spurs at the other fractional frequencies were also less than the existing techniques.