Ferroelectric Capacitor in Paraelectric State Based Adaptive Load for Power Amplifier

Tunable high dielectric constant materials like Barium Strontium Titanate (BST) are finding multiple applications for a variety of circuits such as tunable matching networks, voltage controlled oscillators, as well as active and passive phase shifters. Most of the characterization parameters studied so far depend on the tunability of these devices. Ferroelectric capacitor modelings have primarily focused on accurate prediction of capacitive change versus bias voltage of BST. Another parameter that is very important for high frequency applications is distortion. Considerable work has been reported on the distortion analysis of reverse biased p-n junction diodes for tunability applications. In this dissertation, the characterization of distortion in high-K BST capacitors is reported. The harmonic and intermodulation distortion resulting from ferroelectric capacitors were analyzed using Volterra series and measured using a parallel resonant circuit approach. The measured results have been compared with simulated results based on the non-linearity in capacitance versus voltage characteristics in ferroelectric capacitors.;In order to transfer maximum power to a load, RF amplifiers need matching networks. Ferroelectric capacitors based on materials like BST offer the required flexibility. The impact of input and output matching networks on improving output power and efficiency has been discussed. The simulated power amplifier characteristics have been compared with the fabricated amplifier on an RF PCB board. The measurements show the band-switching and impedance transformation capabilities for input and output matching networks.