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Open AccessArticle

Enhancing Q-Factor in a Biquadratic Bandpass Filter Implemented with Opamps

School of Engineering, Universidad de las Américas Puebla, 72810 San Andrés Cholula, Mexico
Department of Electronics, National Institute for Astrophysics, Optics, and Electronics, 72840 Puebla, Mexico
Faculty of Electronics Science, Benemérita Universidad Autónoma de Puebla, 72000 Puebla, Mexico
Author to whom correspondence should be addressed.
Technologies 2019, 7(3), 64;
Received: 14 August 2019 / Revised: 1 September 2019 / Accepted: 2 September 2019 / Published: 11 September 2019
Active filter design is a mature topic that provides good solutions that can be implemented using discrete devices or integrated circuit technology. For instance, when the filter topologies are implemented using commercially available operational amplifiers (opamps), one can explore varying circuit parameters to tune the central frequency or enhance the quality (Q) factor. We show the addition of a feedback loop in the signal flow graph of a biquadratic filter topology, which enhances Q and highlights that a sensitivity analysis can be performed to identify which circuit elements influence central frequency, Q, or both. In this manner, we show the opamp-based implementation of a biquadratic bandpass filter, in which Q is enhanced through performing a sensitivity analysis for each circuit element. Equations for the central frequency and Q are provided to observe that there is not a direct parameter that enhances them, but we show that from sensitivity analysis one can identify the circuit elements that better enhance Q-factor. View Full-Text
Keywords: biquadratic filter; Q-factor; sensitivity analysis; opamp biquadratic filter; Q-factor; sensitivity analysis; opamp
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Tlelo-Coyotecatl, E.; Díaz-Sánchez, A.; Rocha-Pérez, J.M.; Vázquez-González, J.L.; Sánchez-Gaspariano, L.A.; Tlelo-Cuautle, E. Enhancing Q-Factor in a Biquadratic Bandpass Filter Implemented with Opamps. Technologies 2019, 7, 64.

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