An injection locked sub‐harmonic self‐oscillating mixer for multi‐band operation

A high‐performance X‐band subharmonic self‐oscillating mixer (SOM) is proposed. By using a reconfigurable transistor pair in conjunction with open‐ and 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. 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 −100 dBc/Hz at 10 kHz, without affecting the conversion gains. This is the first demonstration of a multiband subharmonic SOM.