Real phase inverters (PI) can be seen as deviating from the ideal PI exhibiting a +180° phase shift. The deviation is termed “parasitic phase contribution (PPC)” here. We proposed an equivalent model of the PI to reliably extract the PPC which can be of interest when making PI-based couplers compact, for example. All elements of the model but the interdigital capacitors’ capacitances are obtained using formulas. The estimated PPC only deviates from the HFSS and Q3D simulations by a mere 3.5° across a 4-GHz band.

Researcher: Robin Jeanty (簡羅斌)

Phase inverters (PI) are applied to a two-section coupler for size reduction. Positioning PI on particular branches of a coupler turns the structure into a backward coupler, splitting power between the conventional through and isolated ports. Combining an even number of backward coupler topologies results in a forward coupler: four PI appear on the longitudinal branches here. Now, the conventional -90° length of a branch should be attained by the summation of the host branch’s electrical length and the PI’s inductance and capacitance contribution. The higher the PI’s part, the shorter the host branch: compactness is ours!

Researcher: Robin Jeanty (簡羅斌)