Marchand Balun With Air Bridge

摘要

The present invention provides a microwave and millimeter-wave balun. This balun is different from the conventional planar Marchand balun by using three edge-coupled lines instead of two edge-coupled lines and adding a pair of broadside coupled-lines. The broadside couple-lines are achieved by stacking two lines fully overlapped; the upper line is implemented using air-bridges to cross over the bottom line. By combining three edge-coupled-lines and broadside coupled-line, it will make the Marchand balun have a higher coupling coefficient and increase the operation bandwidth. The microwave monolithic integrated circuit (MMIC) mixer based on this invention can provide compact size compared to conventional ones.