A 2.4-GHz Ring-VCO-Based Sub-Sampling PLL With a -70-dBc Reference Spur by Adopting a Capacitor-Multiplier-Based Sub-Sampling DLL. - Teng-Shen Yang; Huai-Yuan Hsieh; Liang-Hung Lu (IEEE Trans. Circuits Syst. I Regul. Pap., 2023)