A Dual-Band Negative Group Delay Circuit with Three-Conductor Coupled Lines

A dual-band negative group delay circuit (NGDC) with three-conductor coupled lines is proposed. The proposed NGDC is composed of a couple of three-conductor coupled lines and two different-width transmission lines connected by two pairs of resistors. The negative group delay (NGD) times can be adjusted separately by the resistors. To verify the design concept, a dual-band NGDC is fabricated and measured. The NGD values of -0.93 ns and -0.82 ns are measured at working frequencies of 1.95 GHz and 2.05 GHz, respectively. The measured NGD bandwidths are 23 MHz for the lower band and 18 MHz for the upper band, in which the return loss and insertion loss are better than 17.0 dB and 1.9 dB.