A comparative study of lock range of injection-locked active-inductor oscillators

This paper presents the first study of the locking mechanism and lock range of injection-locked active inductor oscillators. A comparable study on the phase noise and lock range of active inductor oscillators and corresponding LC oscillators is carried out. Two 2.4 GHz oscillators, one active inductor oscillator and the other passive LC oscillator, are designed in IBM 0.13 μm 1.2 V CMOS technology and analyzed using Spectre using BSIM4 device models. Simulation results demonstrate that the phase noise of the active inductor oscillator is -70.45 dBc/Hz at 1 MHz frequency offset without locking and -117.9 dBc/Hz when locked to an external 2.4 GHz reference of phase noise -126.6 dBc/Hz. The phase noise of the LC oscillator is -105.1 dBc/Hz without locking and -126.1 dBc/Hz when locked. The upper and lower bounds of the frequency of the locking signal at which the injection-locked LC oscillator is locked are 2.4+0.02 GHz and 2.4-0.02 GHz, respectively where those of the injection-locked active inductor oscillator are 2.4+0.24 GHz and 2.4-0.12 GHz, respectively. The lock range of the injection-locked active inductor oscillator is 9 times that of the corresponding injection-locked passive LC oscillator with comparable phase noise.