Compact On-Chip Branchline Coupler Using Slow Wave Transmission Line

摘要

Branchline coupler structure using slow wave transmission line effect having both large inductance and large capacitance per unit length. The branchline coupler structure includes a plurality of quarter-wavelength transmission lines, at least one of which includes a high impedance arm and a low impedance arm. The high and low impedances are relative to each other. The high impedance arm includes a plurality of narrow cells and having an inductance of nL and a capacitance of C/n, and the low impedance arm includes a plurality of wide cells and having an inductance of L/n and capacitance of nC. The wide and narrow cells are relative to each other, and the wide and narrow cells are adjacent each other to form a signal layer having step discontinuous alternative widths.