Analysis and Design of a Wideband, Balun-Based, Differential Power Splitter at mm-Wave

A wideband, low-loss balun-based differential power splitter is studied. The use of lumped double-tuned baluns as key building blocks within a splitter leads to a wideband operation, while avoiding signal crossovers and the detrimental effects associated with them. Moreover, the lack of multiple λ/4 transmission-line sections results in an area-efficient and low-loss structure. A demonstration of this design approach comprising a differential 1-to-4 splitter was EM-simulated at 120 GHz in a 65-nm CMOS process. Full-wave EM-simulations, verifying the performance of this splitter, show a minimum in-band insertion loss of 8.3 dB and a port-to-port isolation of 10 dB (or better) across a 3-dB bandwidth of 40 GHz.