Broadband microstrip coupler for MMICs

The work presented in this paper evaluates the potential for broadening the bandwidth of microstrip couplers in MMICs. The even and odd mode phase velocity equalisation techniques are also examined. A prototype -3 dB quadrature coupler working between 6-18 GHz is designed, simulated and measured, based on the evaluation made. Such a distributed coupler occupies 4.9 mm/spl times/2.6 mm on 200 /spl mu/m thick GaAs, and it can be fabricated as a single metallisation using standard MMIC processes.