Patent ID: 6683510
Filing Date: 2004-01-27
Classification: H01P

Abstract:
A planar balun comprising:a substrate of semiconductor material, said substrate having flat top and bottom surfaces; a metal ground plane layer, said metal ground plane layer covering said bottom surface of said substrate; a first coil pancake and second coil pancake formed in side by side relationship on said flat upper surface of said substrate; said first coil pancake comprising a first pair of interleaved spiral coils in magnetically coupled relationship, and said second coil pancake comprising a second pair of interleaved spiral coils, each of said coils in each of said pairs of spiral coils having first and second ends; said first coil pair defining a spiral of decreasing radius and said second coil pair defining a spiral of increasing radius and said first coil pair comprising a mirror image of said second coil pair; said first end of said first spiral coil of said first pair defining a balun input; said second end of said first spiral coil of said first pair and said first end of said second spiral coil of said second pair being connected electrically in common; and said second end of said second spiral coil of said second pair being an open circuit, wherein said first spiral coil of said first pair and said second spiral coil of said second pair define an open circuit transmission line; a first end of said second coil of said first pair defining a first balun output; said second end of said first coil of said second pair defining a second balun output; and said second end of said second coil of said first pair and said first end of said first coil of said second pair being electrically connected together.