Reconfigurable Three Functional Dimension Single and Dual-Band SDR Front-Ends Using Thin Film BST-Based Varactors

Abstract

This paper presents a performance evaluation of single and dual-band software-defined radio (SDR) front-ends using commercially available barium strontium titanate (BST) thin film to control SDR receivers dynamic range and mitigate interference. Firstly, an SDR front-end solution using a BST-based single-band bandpass filter (BPF) is developed to manage in-band attenuation according to the input power. Secondly, a dual-band SDR front-end to avoid high power interference with its spectral content on the below side of the second band is designed. This device is performed with a BST-based dual-band BPF providing independent control of the power limiting capabilities of the first and second bands. The BST component introduces a dependence on bias voltage, frequency, and input power. Consequently, by applying a 0 V bias, it is possible to target interferers between 700 MHz up to 1 GHz and attenuate them more than 7 dB at 40 dBm. The frequency dependence is defined by the second band, which retains its filtering performance while performing interference cancellation in the first band. This SDR solution implements a three functional dimension device in the upper MHz with a power-dependent insertion loss, high threshold power level, and frequency selectivity.

Keywords

• Dual-band bandpass filters
• ferroelectric devices
• frequency selectivity
• intermodulation distortion
• nonlinear measurements
• power limiters