Compact lumped element ring balun layout

摘要

A lumped element ring balun (60) including elements patterned on a monolithic substrate (62) in a compact design. The balun (60) includes four inductors (64, 66, 68, 70) and a plurality of capacitors (190, 192, 198, 202, 214, 226) electrically coupled together to provide RF output signals that are 180° out of phase with each other. The inductors (64-70) are symmetrically disposed in a rectangular area on the substrate (62). A first pair of the inductors (64, 66) is positioned at one end of the rectangular area, and a second pair of the inductors (68, 70) is positioned at opposite end of the rectangular area. All of the capacitors are formed on the substrate (62) in a central circuit area (72) between the first pair of inductors (64, 66) and the second pair of inductors (68, 70). Inner ends (76, 92, 98, 106) are coupled to circuit elements in the circuit area (72) by a metallized trace (120, 136, 150, 170) extending through an air bridge (124, 140, 154, 174).