Tunable Ferroelectric Ceramic Components for Reconfigurable Wireless Communications

Abstract

This paper focuses on the technology evolvement and novel concepts of ferroelectric microwave components. They aim to enable reconfigurable wireless frontends for frequency-agile, software-defined and cognitive radios. Such components are an emerging technology based on the nonlinear solid state ferroelectric materials like Barium-Strontium-Titanate namely BST thick-films. They are expected to cope with the demands of multiband and multi-standard operation. Processing and integration technologies are revised to enable multilayer component realization, including selective sol-gel printing and vertical connection through laser drilling. Several novel kernel frontend components based on ferroelectric thick-film ceramic are addressed then. The challenging trend of antennas towards compactness with wider spectrum coverage is coped with several tunable resonant modes in the antennas with integrated BST varactors. The optimized prototype for frequency division duplex services covers 1.47 GHz to 1.76 GHz with a variable distance between up- and down-link channels. The environmental impact on antennas can be compensated by tunable matching networks. In the commercial frequency range from 1.8 GHz to 2.1 GHz, a demonstrative module exhibits an insertion loss less than 0.98 dB, in a compact multilayer package. A compact bandpass filter is enabled by an evanescent mode substrate integrated waveguide cavity in ferroelectric ceramics, integrated with tunable complementary split ring resonator scatterers and tunable matching networks. The compact module covers 2.95 GHz to 3.57 GHz with a comparatively low insertion loss.