Synthesis and implementation of superluminal circuits with zero group delay

This paper proposes a novel synthesis and implementation of maximally flat zero group delay (MFZGD) responses for the first time. The proposed synthesis method is more general as one can implement optimized MFZGD filter of any order. It is proved that a lossless network cannot exhibit zero delay response hence loss is necessary for zero group delay. Complete design flow chart with one synthesis example is discussed. The exact agreement between the polynomial and coupling matrix based responses validate the proposed synthesis method. Finally one prototype is fabricated and measured, showing a good agreement between the measured and synthesis responses.