Design and test of a 4:1 balun based on a novel wideband balun topology

This paper showcases a 4:1 balun design based on an inversely magnetically coupled transformer and an autotransformer. By satisfying the proportional relationship between inductances value, the transformer and autotransformer can respectively achieve signal transmission and impedance matching between balanced and unbalanced ports. Analysis indicates that its innovative topological structure can flexibly achieve impedance matching and balanced signal realization within a wide bandwidth. The proposed balun, realized through a 45nm RFE process, the layout size is 170×130 μm². Exhibits test results with S11 greater than 9 dB above 9 GHz in the frequency band. Amplitude and phase differences between balanced signals of less than 1dB and 10°respectively in the 9-16GHz range. The consistency between simulation and test results demonstrates the significant potential for development of this novel balun.