Characterization of Nonlinear Device Capacitance in Frequency Domain

This paper formulates a simple matrix-based solution to estimate the voltage-dependent capacitance of a weakly nonlinear device at microwave and millimeter wave frequencies. Unlike other approaches, which rely on the direct capacitance measurement at different bias voltages, the proposed technique generates a large signal model for the capacitance directly from the frequency domain measurement and the known I-V characteristic. The resulting capacitance versus voltage characteristic can be incorporated as a simulation model into a microwave system design for harmonic balance simulation. Measurement of the capacitance of a highly nonlinear device using this approach agrees with the results of harmonic balance simulation for microwave and millimeter wave frequencies.