Design of a quint-band passive NGDC by using Taguchi’s optimization method

Abstract

This article presents a quint-band passive negative group delay circuit (Q-NGDC) by using Taguchi’s optimization method for the first time. This Q-NGDC mainly consists of a semi-circle and a multi-stub resonator, and it is evolved from a simple NGDC (Type I) to a well-designed one (Type VI) through three optimization stages. It is found that, with the application of Taguchi’s method (TM) in conjunction with full-wave simulations, the efficiency of the designed passive multi-band NGDC has been improved significantly. The proposed Q-NGDC was fabricated and tested, and the experimental results show that the five operation bands have been achieved at the center frequencies of 1.76, 2.80, 3.84, 4.42, and 5.28 GHz, with the corresponding group delay values of −1.85, −2.15, −1.45, −1.6, and −1.1 ns. The measured transmission coefficients are −4.4, −7.8, −9.7, −9.3, and − 8.9 dB. Furthermore, the proposed NGDC shows the best figure of merit (FOM) at each resonant frequency with a relatively small size. The proposed NGDC can be potentially applied to WCDMA, 5G communication, Zigbee (IEEE802.15.4), and Wi-Fi (IEEE802.11n) systems.