Negative group delay circuit based on a multisection asymmetrical directional coupler

In this paper, we present a novel passive negative group delay (NGD) circuit based on directional couplers. By cascading several directional couplers with appropriate coupling coefficients, we are able to synthesize negative group delay with a broad bandwidth at the coupled port of the multisection directional coupler. Unlike conventional NGD circuits that use bandstop structures with lumped elements, such as inductors and capacitors, to realize negative group delay, the proposed design provides a fully distributed realization of NGD circuit. Therefore, this novel NGD circuit is very promising to be integrated into high frequency designs.