Design of a compact ultra wideband balanced-to-balanced power divider/combiner

A compact ultra wideband balanced-to-balanced power divider/combiner based on Finite Ground Coplanar Waveguide (FGCPW) phase inverter is presented. By replacing the λ/2 transmission lines in [1] by FGCPW phase inverters, circuit size of the power divider/combiner has been significantly reduced, from (0.75λ × 0.5λ) to about (0.375λ × 0.125λ). With the wideband property of the FGCPW phase inverter, 3-dB fractional bandwidth of the proposed power divider/combiner can be obtained up to 200%. A -3.7 dB differential-mode transmission coefficient |S_ddAB| and -0.25 dB common-mode reflection coefficients |S_ccAA|, |S_ccBB| have been obtained. Other mixed mode S-parameters are all less than -10 dB from 0.1 GHz to 1.75 GHz. The measurement results agreed well with the simulation results.