A Fully-Reconfigurable Coupler with Lumped Elements

A lumped-element coupler is proposed with fully-reconfigurable power-division ratio, phase difference between output ports, and operating frequency. It is constructed with 8 lumped inductors and 8 variable capacitors. Values of the variable capacitors are functions of the power-division ratio, phase difference, operating frequency and inductors values. The function can be derived through the even-/odd-mode theory. It is shown that the proposed coupler provide a 90 ° ±45° tunable phase difference when maintaining the equal power division at 4.7 GHz, a tunable power division ratio from −15 to 0.6 dB and tunable operating frequency from 4.6 to 8.6 GHz when the phase difference is 90°. The component size can be miniaturized signifi-cantly by using integrated lumped elements.