Robustness of Injection-Locked Oscillators to CMOS Process Tolerances

We present a model for injection-locked oscillator (ILO) phase shifter that includes high-frequency coupling through a Silicon substrate. In this model, we consider conductive and resistive features of the substrate and predict the locking range and phase shift in the presence of substrate coupling. The model is verified through agreement with Cadence simulations and measurements. The phase shifter measurements are verified in a 2 x 2 injection-locked oscillator array operating from 15.5 to 18.5 GHz implemented in 90-nm GlobalFoundries SiGe BiCMOS technology. A 71-86 GHz 2 x 2 phased array uses this injection-locked phase shifter where the high frequency parasitics play an important role in the circuit performance.