Wideband and Compact Impedance-Transforming 90° DC Blocks With Symmetric Coupled Transmission-Line Sections

Wideband and compact 90° dc blocks are presented for the impedance-transforming function and designed based on the transmission-zero movement method combined with the pole (root) split method, which is the reason for the wide bandwidth responses, even with being very compact. For a proof-of-concept demonstration, one prototype is tested, and the measured bandwidth with the 10-dB return loss is 0.74–4.05 GHz (331%) with a design frequency of 1 GHz.