Patent ID: 7746193

Claim:
A 180° hybrid coupler, comprising: a first transmission line transformer and a second transmission line transformer, each comprised of coplanar stripline disposed in a spiral configuration, each coplanar stripline having a first characteristic impedance and configured to function as a balun; a common input feed coupled to each of said first and second transmission line transformers; a third transmission line transformer and a fourth transmission line transformer, each configured to function as a balun and coupled to said first and second transmission line transformers, said third and fourth transmission line transformers each comprised of coplanar stripline disposed in a spiral configuration, said coplanar stripline having a second characteristic impedance different from said first characteristic impedance; a first resistor connected between a second output node of said first transmission line transformer and a second output node of said second transmission line transformer; a second resistor connected between a first output node of said first transmission line transformer and a first output node of said second transmission line transformer; and wherein said first, second, third, and fourth transmission line transformers are configured to produce a first output signal from said third transmission line transformer which is approximately 180 degrees out of phase relative to a second output signal from said fourth transmission line transformer when an input signal is applied to said common input feed.