BROADBAND BALUN FOR MONOLITHIC MICROWAVE INTEGRATED CIRCUIT APPLICATION

We present a compact and broadband balun based on the concept of a synthetic left-handed transmission line and right-handed transmission line. The compact balun uses lumped, discrete LC elements only to reduce the circuit size dramatically. For the frequency range of 0.6-1.2 GHz, this circuit maintains 180 +/- 9.5 degrees phase difference at the outputs, whereas the maximum insertion loss is -1.78 dB, and the minimum return loss is -10.2 dB at all three ports, yet the circuit size is merely 12 x 8 mm(2). As far as we know, this is the smallest broadband balun reported in the literature, and the size can be further reduced, if the circuit is made with a monolithic microwave integrated circuit technology. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54: 203-206, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26468