[3] Cheng S, Tong H, Silva-Martinez J, et al. Design and analysis of an ultrahigh-speed glitch-free fully differential charge pump with minimum output current variation and accurate matching[J]. IEEE Trans. Circuits Syst. Ⅱ: Express Briefs, 2006, 53(9): 843-847.
[4] Choi Y S, Han D H. Gain-boosting charge pump for current matching in phase-locked loop[J]. IEEE Trans. Circuits Syst. Ⅱ: Express Briefs, 2006, 53(10): 1022-1025.
[5] Amer A G, Ibrahim S A, Ragai H F. A novel current steering charge pump with low current mismatch and variation[C]// 2016 IEEE Inter. Symp. on Circuits and Systems (ISCAS), 2016: 1666-1669.