Development of a low-loss multilayered broadband balun using twin-thickness thin-film

We present the development of a multilayered Marchand balun that operates over a 4-20 GHz bandwidth. The balun achieves a measured insertion loss of less than 0.5 dB from 4 to 17 GHz, and less than 0.7 dB from 17 to 20 GHz. Measured amplitude and phase imbalances are less than 0.5 dB and 5°, respectively within 4-20 GHz. The balun design employs a novel twin dielectric thin-film thickness structure to achieve a low insertion loss and a wide bandwidth.