Model and Performance Analysis of Coplanar Waveguide Based on Different Oxide Structure HR-Si Substrate

摘要

Coplanar waveguides (CPW) are widely used in MMICs as interconnects and matching networks. Through conventional CMOS processing, three kinds of 50 Ω CPWs are designed and fabricated on three different types of substrates, including HR-Si (High-Resistivity Silicon) directly, HR-Si with continuous SiO_2 layer and HR-Si with discontinuous SiO_2 layer where the SiO_2 between signal and ground line is etched. Measurement shows that CPW on HR-Si owes the least transmission loss while the one on HR-Si with continuous SiO_2 owes the most loss. The insertion losses at 20 GHz are-0.88dB,-2.50dB and-1.06dB respectively. Based on the two-port network analysis of the equivalent model of the substrates, it has been proved that the major factors influencing the transmission loss are resistivity of substrate, oxide capacitance and coupling capacitance. With this conclusion, the theoretical analysis is consistent with the measured results.