We propose a novel method to multiply the pulse repetition rate of actively mode-locked fiber laser (AMLL) by spectrum-slicing and time-division-multiplexing for photonic analog-to-digital converters (PADC). Self-phase modulation (SPM) is employed to broaden the spectrum in order to obtain more parallel channels. The SPM induces additional phase jitter that degrades PADC’s performance. We theoretically and experimentally show phase jitter can be effectively reduced by precise control of the tunable true-time delay array. Sampling clock of 40 GHz or higher with low phase jitter is achieved based on 10-GHz AMLL, which can be used to realize high performance PADC.