EFFICIENT 2-DIMENSIONAL INTERPOLATION SCHEME SUITABLE FOR NONLINEAR MICROWAVE DEVICE MODELING

The use of device models directly based on measured information is wel l established in nonlinear microwave circuit analysis, and may provide significant advantages over analytic models relying on parameter extr action techniques. These 'database' models always include some sort of interpolation mechanism for overcoming the inherently discrete nature of measured data. This is a delicate aspect, since interpolation may produce unwanted ripples or other ill-conditioning that may considerab ly degrade the model performance. The authors propose a novel two-dime nsional cubic-spline interpolation scheme that guarantees the absence of spurious ripples, and simultaneously provides interpolation of both the measured function and its first derivative.