A Novel Dual-Band Negative Group Delay Circuit With a Stepped-Impedance Structure

Abstract

A novel dual-band negative group delay (NGD) circuit employing an active stepped-impedance structure is presented in this letter. A theoretical analysis on the dual-band NGD response of the proposed structure is presented. The characteristic impedances and phases of the transmission lines are calculated to implement the circuit’s I/O transmission function. This calculation is performed by defining the desired NGD values at two arbitrary frequencies as the operating condition. The theoretical analysis demonstrates that there is no dependence between the group delay (GD) values at different frequencies. Prototypes of the proposed circuit with the same or different GDs are designed, fabricated, and measured to demonstrate the performance of the proposed structure. The experimental results show that the proposed dual-band NGD circuit is capable of generating −1 ns GD at 0.7 and 1.3 GHz or different GDs (−0.3 and −2 ns). The corresponding maximum and minimum transmission gains are 2 and −8 dB, respectively.