Filtering balanced-to-single-ended power dividing network

Abstract

In this article, the filtering balanced-to-single-ended power dividing networks are proposed. Except the fundamental functions of differential-mode transmission, common-mode suppression, and out-of-phase single-ended output ports with isolation, the proposed designs show the advantages of wide controllable range of differential-mode bandwidth, multiple transmission zeros (TZs), and wide bandwidth for high out-of-band suppression. The frequencies of TZs, bandwidth, isolation, and common-mode suppression can be controlled by the parameters. For demonstration, three prototypes (Deigns I, II, and III) with two, four, or six TZs are implemented. The measured results show that design I (II and III) has an insertion loss of 0.38 dB (0.7 dB and 0.8 dB), an operating bandwidth of 12.5% (7.5% and 6.9%), and a bandwidth for 30-dB out-of-band suppression of 0.06f0 (0.09f0 and 0.14f0). The isolation and common-mode suppression inside the passbands of the three prototypes are all larger than 17 and 38 dB, respectively.