Active CPW MMIC Circulator for the 40 GHZ Band

For the first time, several active coplanar circulators have been designed and fabricated for the 40 GHz band. The technology for these circuits is the PM-HFET technology from Daimler Benz in Ulm. The introduced designs utilize the new CPW model library in the CAD package LIBRA. The return loss of the electronic circulator is better than ¿15 dB and the insertion loss is typically ¿3 dB for a bandwidth of about 6 GHz at a center frequency of 40 GHz. The isolation between the ports is better than ¿20 dB in the frequency band. New designs on InP and GaAs have been made for frequencies up to 80 GHz.