Active Distributed Mixers Based on Composite Right/Left-Handed Transmission Lines

Distributed mixers are based on the active coupling of two artificial transmission lines (TLs) and provide ultra-wideband performance. This paper shows that it is possible to design distributed mixers with novel performances if artificial TLs with dispersion diagrams different from those provided by conventional series-inductor/shunt-capacitor TLs are used. In particular, three novel distributed mixers, presenting dual-band/diplexer behavior, with and without image rejection or wideband conversion response with image rejection, are proposed, analyzed, and measured. An ideal continuous model is used to analyze the intrinsic behavior of distributed mixers and to show how to engineer their desired performance by proper design of the phase constants. The limitations derived from the unavoidable discrete implementation of the artificial TLs are also assessed. Finally, three mock-ups are implemented and measured. The experimental results obtained proof these novel distributed mixer concepts and validate the proposed theoretical analysis and design methodology.