This brief investigates the lock range of injection-locked  LC  oscillators using a linear control system approach. It explores the intrinsic relation between the lock range of injection-locked  LC  oscillators and the injection-induced variation of the impedance of the  LC  tank. We show that injection-locked active-inductor  LC  oscillators exhibit a larger lock range, as compared with their passive counterparts. We further show that the large lock range of injection-locked active-inductor oscillators is due to both the low quality factor and the large injection-induced variation of the inductance of active inductors. These findings are validated using an injection-locked passive  LC  oscillator and an injection-locked active-inductor  LC  oscillator designed in IBM 0.13- μm 1.2-V CMOS technology.
['Yushi Zhou', 'Fei Yuan']
A Study of the Lock Range of Injection-Locked CMOS Active-Inductor Oscillators Using a Linear Control System Approach