Compact monolithic spiral quadrature coupler design

The design and performance of two compact monolithic spiral quadrature couplers are presented, employing a novel configuration of mutually coupled coils. The first, designed at 20.35 GHz, occupies 131 × 142 μm and achieves 0.5 dB fractional bandwidth of 19%, with phase error and intrinsic loss below 2.6° and 0.92 dB, respectively. The second, designed at 30.15 GHz with 5.24 dB coupling coefficient, measures 122 × 132 μm and achieves 0.5 dB fractional bandwidth of 30% with a phase difference between 93 and 103°. The insertion loss is smaller than 0.93 dB.