A Novel Dual-Band Negative Group Delay Microwave Circuit

A novel dual-band negative group delay circuit (NGDC) is proposed. The proposed NGDC is composed of an open-circuited transmission line and two resistors connected by two transmission lines. The frequency ratio can be controlled by the characteristic impedance of the transmission lines. To verify the design concept, a dual-band NGDC with the frequency ratio of n = 2 is designed and fabricated. The measured group delay value is -1.03 ns at the center frequencies of lower and upper bands. And the measured NGD bandwidths are 35.2% for the lower band and 16.6% for the upper band, in which the return loss and insertion loss are better than 17.6 dB and 16.9 dB, respectively.