Millimeter Wave E-Plane Transition From Waveguide to Microstrip Line With Large Substrate Size Related to MMIC Integration

Journal article, 2016

This letter demonstrates a packaging concept where a waveguide-to-microstrip transition can be assimilated on a mm-wave MMIC of an arbitrary size and thus avoid the use of bond wires at the high frequency ports of the MMIC circuit. The advantage of the proposed concept is that-it does not require an extra substrate with sub-critical dimensions for the waveguide-to-microstrip transition. The transition can be integrated onto the MMIC, and thus the MMIC can be coupled directly to the waveguide. A Perfect Magnetic Conductor (PMC) surface is used to suppress the unwanted waveguide mode coupling to the oversized circuit cavity. The measured back-to-back transition works over the frequency band 66-98 GHz (relative BW of 38%) with minimum return loss of 12.7 dB. The total insertion loss of the manufactured prototype is found to be 3.26 dB, which also includes a 14.8 mm long microstrip line on an Alumina substrate. The losses in a single transition vary between 0.25 and 0.42 dB.