This article presents a general, time-domain harmonic distortion estimation method, applicable to linear CMOS circuits characterized by weakly nonlinear behavior, ranging from amplifiers, and transconductors to filters, with any number of stages. It offers a compact, fast, and systematic way to model circuits as a structure of interconnected Gm-stages, and estimates the harmonic distortion at every circuit node, providing insight into the distortion contribution of every stage. The method uses a more involved model for each Gm-stage that also accounts for the dependence of its output current on cross-products of its input and output voltages, improving significantly the distortion estimation accuracy. The proposed method is easily implemented in MATLAB, and intends to be integrated as a tool in EDA suites to speed-up distortion estimation. A number of examples are presented, illustrating the application of the method and validating its accuracy via comparison with Cadence Spectre simulation.

Detailed state-space modeling and analysis of a class of RF switched-capacitor power amplifiers achieving high efficiency, output power, and linearity are presented. Time-domain voltage and current waveforms are analytically obtained via the steady-state solution of the amplifier's model equations. The output power of the fundamental and that of the harmonics, as well as the drain efficiency of the switched-capacitor power amplifier (SCPA) are derived. The state-space model is implemented in MATLAB and all theoretical results are compared to Cadence Spectre simulation of the SCPA and are found to be in good agreement.

This work presents a fast and flexible harmonic distortion estimation approach, applicable to linear CMOS circuits. It offers improved accuracy by using a Gm-stage model that includes the dependence of a stage's output current on cross-products of its input and output voltages. The application of the approach is demonstrated in a realistic circuit, and the accuracy of the obtained results is verified by comparison with Cadence Spectre simulation.