RF Small- and Large-Signal Characteristics of CPW and TFMS Lines on Trap-Rich HR-SOI Substrates

The main objective of this paper is to evaluate RF losses and nonlinear behavior of coplanar wave- guide (CPW) and thin-film microstrip (TFMS) lines from room temperature up to 175 °C fabricated on two different types of high resistivity (HR) silicon-on-insulator (SOI) substrates. One standard high-resistivity and one trap-rich (TR) substrates, Soitec RFeSI90 product, are used. It is also shown that by using stacked CPW lines on the TR HR-SOI wafer, transmission lines with performances as high as TFMS lines are achievable, with low losses and low-harmonic distortion, while providing much more flexibility in their design. Through measurements, it is shown that the TR HR SOI substrate shows good stability in terms of losses and linearity up to 120 °C.