Tunable Balanced Power Dividers: An Overview of Recently Developed Balanced Power Dividers and Couplers With Fixed and Tunable Functions

Signal crosstalk and common-mode noise are two issues for engineers when designing today's increasingly complicated microwave integrated circuits [1]. Compared with single-ended circuits, balanced circuits can provide high immunity to environmental noise and broadband common-mode rejection capability [2]. Over the past few years, various balanced passive circuits, such as filters [3], antennas [4], power dividers, and couplers [5]-[17], have been extensively studied. Power dividers and couplers are widely used in microwave integrated circuits, such as antenna feeding networks, balanced mixers, and amplifiers. Balanced couplers are used in double-balanced mixers [18] and balanced frequency doublers [19] to achieve higher efficiency and lower loss.