Low-power divide-by-3 injection-locked frequency dividers implemented with injection transformers

A new divide-by-3 injection-locked frequency divider (ILFD) is proposed. The ILFD consists of a 7.6 GHz voltage controlled oscillator (VCO) and two transformers, which are in series with the cross-coupled transistors in the VCO for signal injection. The proposed CMOS ILFD has been implemented with the TSMC 0.13 mu m CMOS technology. At the supply voltage of 0.8 V, the core power consumption is 1.25 mW, and the free-running frequency of the ILFD is tunable from 7.2 to 7.87 GHz. At the input power of 0 dBm, the total divide-by-3 locking range is from 21.56 to 23.63 GHz as the tuning voltage is varied from 0.0 to 0.8 V. The phase noise of the locked ILFD output is lower than that of the free-running ILFD in the divide-by-3 mode.