Forward/backward coupled ring based phasers for real-time signal processing

A backward and forward coupled ring transmission line all-pass phasers are presented, and their general characteristics, operation principles and typical group characteristics are discussed using ideal circuit simulations. The first configuration is based on contra-directional (backward) coupling, which is perfectly TEM, while the second configuration is based on non-TEM co-directional (forward) coupling, which is the radio-frequency counterpart of the optical ring resonator coupling. Compared to conventional end-connected coupled-line phasers, the group delay swings of the proposed phasers are inversely proportional to the involved coupling coefficients. They thus represent practically promising devices for high-resolution real-time radio.