Arbitrary Prescribed Wideband Flat Group Delay Circuit for Self-Interference Cancellation Circuits

This paper presents a design of arbitrary specified wide flat group delay (GD) circuit without any cross-coupling among non-adjacent resonators. The proposed structure consists of short-circuited coupled lines along with transmission lines (TLs) at input and output. The additional TL provides an extra degree of freedom to obtain higher wideband flat GD without fabrication difficulty in microstrip technology. The close-form analytical design equations are derived to obtain arbitrary wideband flat GD response. For experimental validation, a prototype circuit was designed and fabricated for GD of 3.6 ns at the center frequency of 2 GHz.