A High-Performed Sub-Harmonic Self-Oscillating Mixer for Modern Wireless Communication System

A high-performance X-band sub-harmonic self- oscillating mixer (SOM) is proposed. By using a re-configurable transistor pair in conjunction with an open and a short circuit stubs, the proposed SOM is capable of down converting four RF frequency bands with center frequencies at 7.35, 8.65, 11.35 and 12.65 GHz with a conversion gain ranging from 7.83 to 18.7 dB with very high power-added-efficiency. The measured phase noise of the free-running oscillation is -85.4 dBc/Hz at an offset frequency of 100-kHz. With injection locking, the phase noise is reduced to less than -100dBc/Hz at 10-kHz, without affecting the conversion gains. This is the first demonstration of a multi-band sub-harmonic SOM.