Patterned Permalloy and Barium Strontium Titanate Thin Film Enabled Tunable Slow Wave Elements for Compact Multi-Band RF Applications

We have designed and proposed tunable slow wave RF elements enabled with patterned Permalloy (Py) and barium strontium titanate (BST) nano thin films. A slow wave element structure with discontinuous signal width is designed and implemented in an IBM 45 nm CMOS technology. Effects of pitch length and signal width ratio on slow wave effects are discussed. Inductance variations of Py embedded transmission lines for different dc levels are studied, and capacitance variations of BST thin film are investigated and measured. Results show that the designed slow wave element can have both 2:1 inductance and capacitance tuning ratio with 50 mA dc current and 5 V voltage applied respectively. Multi-band, multi-functionality RF components with miniaturized size can be achieved using this design.