A 600-μm² Ring-VCO-Based Hybrid PLL Using a 30-μW Charge-Sharing Integrator in 28-nm CMOS. - Shiheng Yang; Jun Yin 001; Tailong Xu; Taimo Yi; Pui-In Mak; Qiang Li 021; Rui Paulo Martins (IEEE Trans. Circuits Syst. II Express Briefs, 2021)