Compact and low-loss wilkinson power divider using a high-Q spiral inductor on a sapphire substrate

In this article, a high-performance Wilkinson power divider (WPD) using lumped elements on a sapphire substrate is presented. The proposed WPD is achieved by replacing the transmission line of the conventional WPD with a π-type equivalent circuit. It has a thick metal spiral inductor, and an organic layer, with thicknesses of 40 and 60 μm, respectively, and the Q-factor was 47 at 2 GHz. The measurement result shows excellent RF performance with return loss (S₁₁) and isolation (S₂₁) better than 15 and 12 dB, respectively, and the average insertion loss is lower than 0.3 dB in the operating bandwidths of 3.2 to 4.2 GHz and 6.3 to 10 GHz.