A Wide Locking Range LC-Tank Injection-Locked Frequency Divider

This letter proposes a wideband injection-locked frequency divider (ILFD) and describes the operation principle of the ILFD. The circuit is made of a differential CMOS LC-tank oscillator and is based on the direct injection topology. The wideband function is obtained by tuning the switch across the tank inductors. 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 dual-band divider free-running frequencies are from 1.77 to 2.17 GHz for the low-band mode, and from 2.59 to 3.2 GHz for the high-band mode. At the incident power of 0 dBm, the locking range is about 1.7 GHz from the incident frequency 3.31 to 5.01 GHz at low band and 4.06 GHz from 3.94 to 8.0 GHz at high-band mode. The circuit can be used as a single wideband ILFD.