A Wide Locking Range Differential Colpitts Injection Locked Frequency Divider

This letter proposes a new wideband Colpitts injection locked frequency divider (ILFD) and describes the operation principle of the ILFD. The circuit consists of a differential CMOS LC-tank oscillator and a direct injection topology. The divide-by-two ILFD can provide wide locking range, and the measurement results show that at the supply voltage of 2.4 V, the tuning range of the free running ILFD is from 4.46 to 5.6 GHz, about 1.14 GHz, and the locking range of the ILFD is from 8.03 to 11.63 GHz, about 3.6 GHz, at the injection signal power of 0 dBm. The ILFD dissipates 19.92 mW at a supply voltage of 2.4 V and was fabricated in 1P6M 0.18 mum CMOS process. At the tuning voltage of 1.2 V, the measured phase noise of the free running ILFD is -110.8 dBc/Hz at 1 MHz offset frequency from 4.94 GHz and the phase noise of the locked ILFD is -135.4 dBc/Hz, while the input signal power is -4 dBm.