Design and Simulation of a 1:4 Balun Using Transformer and Autotransformer

This paper presents the design of a 1:4 impedance ratio balun constructed from an inversely magnetically coupled transformer and an autotransformer. The proposed topological structure achieves excellent impedance matching and exhibits lower insertion loss within integrated circuit processing. Comparative analysis against traditional balun structures indicates enhanced flexibility in achieving impedance matching while sustaining broadband operation. Utilizing the 45 nm RF SOI process, circuits employing this balun exhibit an overall insertion loss of less than 1.5 dB across the frequency range of 8.3 GHz to 18.5 GHz.