Maximally Flat Negative Group-Delay Circuit: A Microwave Transversal Filter Approach

• Published in: IEEE transactions on microwave theory and techniques Vol. 62; no. 6; pp. 1330 - 1342
• Main Authors: Wu, Chung-Tse Michael, Itoh, Tatsuo
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplifiers; Anomalous dispersion; Applied sciences; Circuit properties; Circuits; Delays; directional couplers; dispersion engineering; Distributed amplifiers; distributed amplifiers (DAs); Electric, optical and optoelectronic circuits; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Equations; Exact sciences and technology; Flats; Group delay; Mathematical analysis; Mathematical model; Microwave circuits; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwave filters; Microwaves; negative group delay (NGD); Skewed distributions; Transfer functions; Transversal filters; Passive component; Directional coupler; dispersion engineering; negative group delay (NGD); Microwave filter; Anomalous dispersion; transversal filters; Delay circuit; Distributed amplifiers; directional couplers; Coupling coefficient; distributed amplifiers (DAs); Maximaly flat response; Transverse filter; Group delay
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2014.2320220

A comprehensive method to synthesize negative group delay (NGD) in the microwave regime with a maximally flat response is proposed in this paper. This method is based on transversal-filter topologies; it will be shown that by choosing proper coupling coefficients of each tap of a transversal filter, we can realize NGDs with maximally flat characteristics at the output of the transversal filter. The desired coefficients to realize maximally flat NGDs with various amount of group delay are analytically derived and tabulated in this paper. Furthermore, the results are verified experimentally through microwave transversal-filter approaches in both passive and active ways using multi-section asymmetric directional couplers and distributed amplifiers.