A Low Voltage Divide-by-4 Injection Locked Frequency Divider With Quadrature Outputs

This letter presents a low voltage quadrature divide-by-4 (divide4) injection-locked frequency divider (QILFD). The QILFD consists of a 1.8-GHz quadrature voltage controlled oscillator (QVCO) and two NMOS switches, which are inserted into the quadrature outputs of the QVCO for signal injection. The low-voltage CMOS divide4 QILFD has been implemented with the TSMC 0.18-mum 1P6 M CMOS technology and the core power consumption is 3.12mW at the supply voltage of 1.2V. The free-running frequency of the QILFD is tunable from 1.73 to 1.99GHz, the measured phase noise of QILFD is -118dBc/Hz at 1-MHz offset from the free running frequency of 1.82GHz. At the input power of 0dBm, the total locking range is from 6.86 to 8.02GHz as the tuning voltage is varied from 0 to 1.2V. The phase noise of the locked output spectrum is lower than that of free running ring oscillator by 11dBc/Hz. The phase deviation of quadrature output is about 0.8deg