Chip type spiral broadside coupled directional couplers and baluns using low temperature co-fired ceramic

Chip monolithic directional couplers and baluns have been gaining popularity due to the increasing demand of wireless telecommunication equipment. These multilayer components are meeting demands by allowing for smaller board space requirement, ease of surface mount assembly and their relative low cost. Spiral Broadside Coupled Striplines (SBCS) using Low Temperature Co-fired Ceramic (LTCC) are presented as a novel technique of fabricating the ultra-miniature chip directional couplers and the baluns. SBCS structure contributes dramatically to the reduction of the board space and the height compared with conventional Broadside Coupled Striplines (BCS). Electromagnetic principals, structures, electrical properties including scattering parameters (S-parameters) and power handling capabilities of the ultra-miniature chip directional couplers and the baluns utilizing SBCS structure are introduced. In addition, the rapid development and quality advantages of LTCC SBCS structures are discussed.