GD analysis of arbitrary terminated PD with an unequal power-dividing ratio

This study presents the group delay (GD) analysis of an arbitrary terminated unequal power-dividing ratio of a power divider (PD) combined with a negative group delay (NGD) circuit. The proposed circuit can provide an arbitrary prescribed positive group delay (PGD) between ports 2 and 1, whereas it can provide NGD between ports 3 and 1. From analytical analysis, it is found that the magnitude and GD of the PGD path depend only on the power-division ratio, whereas the magnitude and GD of the NGD path depend on the power-division ratio as well as the on NGD circuit. For an experimental verification, the arbitrary terminated unequal PD was designed, fabricated, and measured at the centre frequency of 2.14 GHz. The measurement results are in good agreement with the simulation and predicted theoretical results. For the NGD bandwidth and magnitude flatness enhancement, coupled-line NGD circuits with slightly different centre frequencies connected in parallel were designed and fabricated providing wider bandwidth than the single stage and showed a practical applicability.