A C-band wide locking range injection locked oscillator based phase shifter

Limited locking range in injection locked oscillator based phase shifter (ILPS) is of main concern when used in the local oscillator (LO) path of phased-array systems. This severely limits their use due to failure to lock the free-running oscillator. To overcome this limitation this paper proposes a wide locking range ILPS in the C-band (4 to 8 GHz). The design is aimed to achieve wide locking range at low injection power. Wide locking range is achieved by means of self injection in a CMOS cross-coupled oscillator which reduces oscillator power in a controlled way. The ILPS achieves a locking-range of 3 GHz at 5.3 GHz center frequency under fundamental injection at 0 dBm input power. The ILPS is implemented in a 90-nm RF CMOS process and consumes only 25mW DC power under a 1.8V supply.