Miniaturized 20 GHz CPW quadrature coupler using capacitive loading

This paper describes coplanar waveguide (CPW) quadrature couplers that util ize metal-insulator-metal (MIM) capacitors at each corner, eliminating the need for air bridges and significantly reducing the coupler footprint. A 20 GHz coupler on high-resistivity silicon with branch lengths of 40 degrees (660 mum) is presented-the area is 80% smaller than a conventional design. A measured insertion loss of similar to 4.5 +/- 0.5 dB was achieved at 20 G Hz. (C) 2001 John Wiley & Sons, Inc.