Analysis of a new approach for tunable and reduced size balanced amplifier using thin-film BST varactors

A new approach for tunable balanced power amplifier (PA) using barium-strontium-titanate (BST) varactors is presented and analyzed. Tunable PA utilizes the idea of reduced size tunable branch-line couplers, comprising of BST Varactors. The simulation results indicate the feasibility of balanced amplifier from 1500 to 2500 MHz in terms of gain, reflection coeffecients, and stability. The key features of the presented design are the stability of traditional balanced PA, frequency agility and 50% size reduction due to the use of reduced size branch-line couplers.