Innovative Theory on Multiband NGD Topology Based on Feedback-Loop Power Combiner

The signal delay is one of the main issues encountered during the design and fabrication of the RF/microwave electronic circuits and systems. Therefore, the correction process is constantly needed for the signal delay cancelation. This brief introduces an innovative theory of a microwave circuit topology delay suppressor. The original circuit was originally built with a passive power combiner (PWC) in feedback with an interconnect transmission line (TL) without the use of lossy lumped elements. The theoretical formulation proves that the distributed passive circuit is capable of generating the negative group delay (NGD) phenomenon. The synthesis relations enabling us to determine the circuit parameters in function of the desired NGD value are established. The innovative NGD circuit properties are elaborated. The NGD concept validation was verified with the design of fully distributed passive NGD cell built with a Wilkinson PWC in feedback with a lossy transmission line. The influence of the feedback line attenuation on the NGD function and S-parameters is discussed. A multiband NGD of about -0.7 ns was exhibited over the frequency band of about 0.12 GHz. This distributed NGD topology can be integrated and is useful for the microwave signal delay improvements.