Micro-coaxial lines for active hybrid-monolithic circuits

This paper discusses fundamental properties of rectangular micro-coaxial lines fabricated in the PolyStratatrade process for broadband applications from 2-20 GHz. The possible impedance ranges for coaxial lines implemented with both five and eleven Cu layers are discussed and compared with measured results for the lowest impedance (8 Omega) line. Power handling and thermal properties of these miniature lines are analyzed and measured. A 50 Omega line with outer conductor cross-section of 600 mum by 400 mum is experimentally shown to handle 53 W at 2:5 GHz with a 10% duty cycle. Integration with active components is investigated and a 1-10 GHz measurement of a GaN 50 Omega MMIC amplifier shows minimal performance degradation relative to on-wafer measurements.