New Balance-Applications for Dual-Mode Ring Resonators in Planar Balanced Circuits (Application Notes)

Recently, 4G and 5G microwave communication circuits and systems have been undergoing rapid development [1], [2]. Signal crosstalk and high costs have seriously limited the fast development of microwave technology and multilayer integrated circuits [3], while radiation power loss of commonmode noise can be up to 25% of the input power in the Ka band (22-27 GHz) [4]. For the past 10 years, different balanced circuits with higher immunity to environmental noise, lower electromagnetic interference, and better dynamic range have attracted increasingly more attention [4], [5]. Balanced filters [6]-[15], balanced power dividers [16]-[22], and crossovers [23]-[27] are the most commonly used planar balanced circuits. In our opinion, for passive balanced circuits, some simple design objectives can be summarized as follows: 1) simpler balanced circuit structures, 2) high passband selectivity and wideband harmonic suppression for the differential mode, and 3) wideband and high-level commonmode suppression.