Wideband Frequency Synthesizer at X/Ku Band by Mixing and Phase Locking of Half Frequency Output of VCO

摘要

A wideband low phase noise frequency synthesizer at X/Ku band has been developed by using phase locking and mixing technique at half frequency of voltage controlled oscillator (VCO). The half frequency output signal of the VCO is down converted by a balanced mixer at C band to obtain an intermediate frequency (IF) signal used for phase locking of the VCO. An ultra low phase noise local signal source at 6 GHz is developed with a frequency multiplying chain driven by a 100 MHz oven controlled crystal oscillator (OCXO). Coupling circuit outside the VCO chip to the mixer does not need to be specially designed, which is beneficial to simplify the circuit scheme and improve the phase noise performance. Measurement results show that the phase noise of the output signal at 10.6 GHz to 11.8 GHz and 12.3 GHz to 13.0 GHz is better than −102 dBc/Hz at 10 kHz away form the carrier center. This frequency synthesizer can be used as local signal source or driving source for the development of wideband millimeter-wave frequency synthesizer systems.