Design and performance of a x4 millimeter wave subahrmonic mixer

Due to the relative complexity and cost of MM-wave oscillators it makes sense to use subharmonic mixers, which require local oscillators at much lower frequencies. However, the conversion loss of subharmonic mixers is usually much higher compared to regular mixers, and this limits their use. In this paper we present a new x4 subharmonic mixer with enhanced performance. The mixer operates in the range 37-40 GHz with 2.5 GHz IF frequency. It uses an X band LO, and its conversion loss is around 9 db. The good performance, which is very close to the theoretical prediction, is achieved by idler recovery. To our knowledge this is the best performance reported so far for this type of mixer.