Monolithic integrated 210 GHz couplers for balanced mixers and image rejection mixers

A Lange coupler and a Wilkinson power divider have been successfully realized using a metamorphic high electron mobility transistor (mHEMT) monolithic microwave integrated circuit (MMIC) process to enable the integration of balanced mixers and image rejection mixers above 200 GHz. Prior to manufacturing the coupler performance has been verified on basis of 3D EM-simulations. The measurement results have been compared to the simulations up to 220 GHz demonstrating an excellent agreement. A measured insertion loss of only 0.8 dB for the Wilkinson divider and 1.4 dB for the Lange couplers has been achieved at 210 GHz. The four fingers Lange coupler shows a measured +/- 1 dB coupling bandwidth of 46 GHz from 174 - 220 GHz. The measured return loss is better than 12 dB for the Lange coupler and better than 14 dB for the Wilkinson divider. The measured isolation stays well above 20 dB for both couplers.