Optimization of injection locked frequency divider with tunable active inductor

This paper presents an optimized injection locked frequency divider (ILFD) with multiple division ratios. The divider core is composed of a tunable active inductor (TAI) and cross-coupled transistors. Different tuning voltages are applied to control the impedance of this TAI hence to achieve multi-division ratios of 2, 3, 4 and 5. Key considerations such as operating frequency, locking range, power consumption and input sensitivity of this ILFD are analyzed in detail, based on which an optimized ILFD is designed and fabricated in TSMC 65nm CMOS technology. Measurement results show the proposed design exhibits a high figure of merit.