ABSTRACT
Monolithic microwave integrated circuits (MMICs) have been realized in the past primarily using III–V semiconductor technologies, predominantly GaAs. Comparing silicon germanium (SiGe) and GaAs MMICs, one realizes that another difference is in the circuit complexity, in the number of individual functions integrated on a single chip, and in the total chip size. The designer of silicon MMICs, including silicon (Si)–SiGe, will often have to live with substrate resistivities ranging from 20 Ω cm to may be 1000 Ω cm. In spiral inductors, patterned ground shields are often used which not only reduce substrate loss and ground-coupled noise, but where the shield pattern can strongly reduce Eddy currents in the substrate which otherwise would lower both the inductance and the quality factor. Models for the coplanar transmission lines on the virtual SiGe substrate were developed using test structures on similar wafers and fitting the parameter set for coplanar transmission lines in Agilent ADS, which was also used for the complete circuit design.
