Analysis of Interconnect Line Coupled With a Radial-Stub Terminated Negative Group Delay Circuit

This article introduces a negative group delay (NGD) analysis of interconnect line coupled with a radial stub terminated line. The NGD topology equivalent model is established by considering the microstrip interconnect line and radial stub circuits. The S-parameter and the group delay are expressed as a function of NGD fully distributed topology parameters. The NGD optimal frequencies and existence condition are originally established as a function of the coupler and the associated RLC-network parameters. It was innovatively shown that the proposed NGD circuit presents a property to generate double NGD center frequency. A proof-of-concept designed and implemented in the microstrip technology was simulated and fabricated to validate the NGD concept. Simulated and measured results are in good correlation with the NGD theoretical prediction. The prototype test results confirm the NGD characteristics as -2.1 ns NGD level at the 1.34-GHz center frequency over 56-MHz bandwidth.