A wide-band GaAs monolithic spiral quadrature hybrid and its circuit applications

The design, performance, and circuit applications of a 2-6-GHz GaAs monolithic spiral quadrature coupler are presented. This 90 degrees coupler uses lumped spiral inductors and metal-insulator-metal (MIM) capacitors and is very small in size (14 mil*26 mil). The measured relative phase difference between the coupled and direct port over the 3:1 bandwidth was 93 degrees +or-6 degrees . Applications of this broadband hybrid in reflection phase-shifter, image-reject downconverter, and I-Q downconverter circuits have also been successfully demonstrated based on this structure.<
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