Volterra Analysis Using Chebyshev Series

The paper presents a new approach to the Volterra analysis of analog circuits. This kind of analysis is widely used for the calculation of distortion and intermodulation products. However, the analysis is limited to circuits with small signal excitations and becomes inaccurate when the input signal amplitude increases, especially when MOSFETs are involved. In this paper, the authors analyze the reasons of this drawback, which is no other than the Taylor series´ convergence properties. Furthermore, the authors propose a solution, by calculating the nonlinearity coefficients using a different type of polynomial expansion, the Chebyshev series. The authors also present results comparing Chebyshev series performance with other types of polynomial expansions. Finally, the authors apply the proposed method to analyze the intermodulation distortion (IMD) of a CMOS RF power amplifier.