Quadrature Injection-Locked Frequency Divider ÷2 for Radio Frequency Interference Reduction

This article presents a wide-locking range divide-by-2 quadrature injection-locked frequency divider (QILFD) with capacitive cross-coupled oscillator. The ILFD consists of a quadrature voltage-controlled oscillator (QVCO) and two NMOS switches, which are in parallel with the QVCO resonators for signal injection. The proposed CMOS QILFD has been implemented with the tsmc 0.18-µm CMOS technology and the core power consumption is 20.4mW at the supply voltage of 1V. At the input power of 0dBm, the divide-by-2 locking range is 90.322% from 3.4 GHz to 9.0 GHz. The phase noise of the locked output spectrum is lower than that of free running QILFD in the ÷2 mode for RFI reduction