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Measurements of low frequency noise in Si and Si0.64Ge0.36 p-channel metal oxide semiconductor field effect transistors are compared with a model of carrier number fluctuations due to tunneling into an energy independent density of oxide trap states (Nox) and associated mobility fluctuations. The failure of the model to explain the data leads us to suggest that reduced noise in the SiGe device as compared to Si is primarily associated with an energy dependence of Nox and a displacement of the Fermi level at the SiO2 interface in the heterostructure relative to the Si control.

Measured propagation characteristicsof Finite Ground Coplanar (FGC) waveguide on silicon substrates with resistivities spanning 3 orders of magnitude (0.1 to 15.5 Ohm cm) and a 20 I.tm thick polyimide interface layer is presented as a function of the FGC geometry. Results show that there is an optimum FGC geometry for minimum loss, and silicon with a resistivity of 0.1 Ohm cm has greater loss than substrates with higher and lower resistivity. Lastly, substrates with a resistivity of 10 Ohm cm or greater have acceptable loss.

Abstract-Finite-ground coplanar (FGC) waveguide lines on top of polyimide layers are frequently used to construct three-dimensional Si-SiGe monolithic microwave/millimeter-wave integrated circuits on silicon substrates. Requirements for high-density, low-cost, and compact RF front ends on silicon can lead, however, to high crosstalk between FGC lines and overall circuit performance degradation. This paper presents theoretical and experimental results and associated design guidelines for FGC line coupling on both high-and low-resistivity silicon wafers with a polyimide overlay. It is shown that a gap as small as 6 m between two adjacent FGC lines can reduce crosstalk by at least 10 dB, that the nature of the coupling mechanism is not the same as with microstrip lines on polyimide layers, and that the coupling is not dependent on the Si resistivity. With careful layout design, isolation values of better than 30 dB can be achieved up to very high frequencies (50 GHz).Index Terms-Coplanar waveguide (CPW), coupling, crosstalk, finite difference time domain (FDTD), finite ground coplanar (FGC) waveguide, monolithic microwave integrated circuit (MMIC), polyimide.