Tunable and flexible Barium Strontium Titanate (BST) varactors on Liquid Crystal Polymer (LCP) substrates

Tunable inter-digital capacitors (IDCs) are presented on flexible Liquid Crystal Polymer (LCP) substrates for the first time. Barium Strontium Titanate (BST) ferroelectric material is used as the tuning mechanism. A unique transfer process has been implemented to realize the BST thin film on the LCP substrate. In addition, due to the monolithic integration process, there is no wire bonding or packaging. This has allowed for successful demonstration of tunable and flexible IDCs up to 50 GHz. Tunability of 22–28% and Q factors of 80–7 have been measured in the frequency range of 0.01–50 GHz. To our knowledge, this is the first demonstration of a tunable ferroelectric device on 100% flexible materials without the use of any rigid components. This technology will have a wide range of applications in new generation of agile, high-frequency, and flexible electronics.