This thesis explores advances in microwave passive device design, focusing on balanced circuits (filters, diplexers, couplers) to achieve improved common-mode rejection. It investigates novel designs for both planar and 3D printed devices. Planar balanced circuits form the core of this research, with designs including a dual-band bandpass filter, miniaturized balanced diplexers (dual-band and tri-band), a new alternative to T-junction based diplexers, and a differential coupled-line directional coupler. These designs offer advantages such as good isolation and strong common-mode rejection. The thesis also explores the application of glide symmetry to the design of common-mode rejection filters, demonstrating significant improvements in filter performance. Finally, the research ventures into the cutting-edge field of 3D printed filters. Using stereolithography (SLA) with copper plating, this work presents monolithic compact bandpass filters based on capacitivelyloaded intertwined helical resonators. This innovative approach demonstrates the potential of 3D printing for future microwave device development. Overall, this thesis contributes to the field by proposing novel balanced circuit designs and exploring the potential of 3D printed microwave devices. These findings provide valuable insights for the ongoing development of high performance and compact microwave devices.