Nonlinear Properties of Si-based substrates for wireless systems and SoC integration

The nonlinear behaviour of silicon substrates with different resistivities is analyzed using coplanar structures. In order to compare the nonlinear performance for different substrates and technologies, the harmonic distortion of crosstalk test structures is investigated, as well as the dependence on the distance. The generated harmonic components due to a large signal at 900 MH are measured using a one-tone network analyzer based setup. Below the crosstalk tap, harmonic levels as high as -43 and -54 dBc for 15 dBm are generated for standard and high-resistivity (HR) Si substrate, respectively. The introduction of a trap-rich layer at the interface between the BOX and the high-resistivity Si (HR-Si) provides a reduction of at least 45 dB in the harmonic distortion generated into the substrate. It has been proven that these results can be easily extrapolated to crosstalk structures with different dimensions.