A 2.7 V, 5.2 GHz frequency synthesizer with 1/2 - subharmonically injection-locked distributed voltage controlled oscillator

A 2.7 volt, 5.2 GHz frequency synthesizer has been implemented. A phase locked loop simultaneously controls the oscillation frequency of both the 2.6 GHz injection source and the 5.2 GHz distributed voltage controlled oscillator. The intrinsic frequency mismatch between the 2.6 GHz voltage controlled oscillator and the 5.2 GHz distributed voltage controlled oscillator is resolved by performing 1/2-subharmonically injection locking on a 5.2 GHz distributed voltage controlled oscillator. The locking range due to various injection powers and harmonic levels are measured. Investigation on the locking characteristic shows that the locking range is not only affected by the fundamental of the injected signal, but also strongly dependent on the magnitude of the second harmonic of the injected signal. The findings provide insight for the design of wide locking range synthesizer. The developed low-voltage frequency synthesizer caters for wireless LAN applications. With slight modifications, the oscillator can be applied to ASIC design.