A ring-oscillator-based wide locking range frequency divider

This letter proposes a wide locking, range injection locked frequency divider (ILFD) and describes the operation principle of the ILFD. The circuit is made of a dual band two-stage differential complementery metal-oxide-semiconductor (CMOS) ring oscillator and is based on MOS switches directly coupled to the differential outputs of the ring oscillator. The divide-by-two ILFD can provide wide locking range and the measurement results show that at the supply voltage of 1.8-V, the divider free-running frequencies are 1.36 GHz and 2.3 GHz, and at the incident power of 0 dBm, the locking range is about 1.75 GHz from the incident frequency 1.9 GHz to 3.65 GHz at low band and 2.55 GHz from 2.95 GHz to 5.5 GHz at high hand.