A 0.6-V Minimum-Supply, 23.5 ppm/°C Subthreshold CMOS Voltage Reference With 0.45% Variation Coefficient. - Huang, Chenyu; Zhan, Chenchang; He, Linjun; Wang, Lidan; Nan, Yang (IEEE Transactions on Circuits & Systems. Part II: Express Briefs, 2018)