Wideband Flat Negative Group Delay Circuit With Improved Signal Attenuation

A novel wideband flat negative group delay (NGD) circuit with improved signal attenuation is proposed. The proposed negative group delay circuit (NGDC) is composed of three transmission lines and two parallel branches, which are consisted of two series transmission lines with a resistor linking to a T-type stub. The complete closed-form design equations are presented. For verification, an NGDC is designed, fabricated, and measured at the center frequency of 2.14 GHz. From the measured results, NGD time of −1.11 ns at the center frequency is obtained with an insertion loss of 9.75 dB and return loss of 22.3 dB. The flat-NGD bandwidth reaches 6.1% from 2.072 to 2.202 GHz with ±11.5% group-delay fluctuation.