THE USE OF ACTIVE TRAVELING-WAVE STRUCTURES IN GAAS MMICS

A coplanar waveguide has been fabricated on a modulation doped GaAs su bstrate in order to evaluate the potential of traveling-wave structure s in microwave applications. The use of a Schottky contact center cond uctor enables the line to function as a slow wave structure in which t he rf propagation characteristics can be modified with a de bias, Meas urements are reported at 10 GHz on simple structures, some of which in corporated an additional dielectric layer, Results show that slow-wave factors of between 8 and 24 are readily obtained with a loss per slow -wave factor was about 0.7 dB/mm. The practical issues relating to the application of such structures in phase shifters, chip size reduction , compact active filters and resonators are examined.