Miniature MMIC star double balanced mixer using lumped dual balun

The authors present the design and performance of a very compact MMIC star mixer. The mixer is composed of four diodes and two lumped dual baluns which are realised using two high/low-pass out-of-phase power splitters in parallel. The MMIC star mixer shows wide bandwidth, high PldB, high third order intercept (IP3) point and high port-to-port isolations both in the applications of up and down converter. The chip size of this star mixer is much smaller than those of the conventional mixers. To the best of the authors' knowledge, it is the smallest size ever reported for passive mixer operated at S-band.