Frequency Divider Using Hybrid Transformer-based and Resistively Distributed Resonator

This paper presents a high-performance wide-band divide-by-2 injection-locked frequency divider (ILFD) in the 0.18 μm CMOS process. The ILFD consists of two sub-ILFDs. The first sub-ILFD designs a 4th order resistively distributed resonator, and the 2nd ILFD designs a 2nd order LC resonator. Two sub ILFDs use two transformers to inductively couple each other, and the ILFD employs a triple-resonance resonator with three resonant frequencies. The ILFD designs 3 frequency bands at 3.8 GHz, 3.4 GHz and 2.6 GHz by tuning the varactor capacitance. At low injection power, the ILFD designs three locking ranges correlative with the oscillation frequency bands. Overlapped locking range associated with two and three resonant frequencies are found when injection power of 0 dBm.