| 摘要 |
Active directional couplers are provided. In accordance with certain embodiments of the invention, the subject active directional couplers are tunable. The tuning is accomplished via varactors connected to the lines of the active directional couplers. Active directional elements are provided between different lines of the subject active directional couplers to control a signal path between ports of the different lines. The active directional elements are selected from diodes, transistors, inverting amplifiers, non-inverting amplifiers, differential amplifiers, and active baluns. The lines include a phase shift element between the two ports of each line. The phase shift element is selected from a transmission line, a delay line, and a phase shifter. Advantageously, the subject lines do not have to be designed for ideal phase shifting and can be designed at near 90° or nearλ/4 values. |
