N-Path Filtering and Mixing Analysis—A General Approach Based on Fourier Transform
Florence Podevin, Imadeddine Bendjeddou, Fadel Mohsen, Catalin Andrei Dobrin, Sana Ibrahim, A. Al Shakoush, M. Diallo, Jordan Corsi, L. Vincent, Manuel J. Barragán, Sylvain Bourdel · IEEE Transactions on Circuits and Systems I Regular Papers · 2024
This article proposes a general approach to accurately model the N-path filters and mixers, with the double purpose of bringing a better insight in the frequency transposition phenomena and opening the door towards a more general discussion concerning NPF-NPM and their outstanding properties as passive circuits. Thanks to a Fourier transform analysis, some mathematical equations are rigorously derived for both filtering and mixing voltage gains. The analysis is compared with ideal simulations for various sets of parameters: source impedance$R_{a}$, load impedance$R_{L}$, switch resistance$R_{sw}$, capacitive path$C_{L}$. Some error curves are extracted validating the initial hypotheses for the model in a given range of capacitances values. As a proof of concept, it is shown that the model complies with the measurements results with very good accuracy. The error is less than 10.5% on the two first harmonics prediction.