Abstract
This paper presents a systematic study of a compact and reconfigurable periodic structure in GaAs MMIC technology. Compactness is achieved by the introduction of spiral inductors in a conventional unit cell without disturbing the reactive loading mechanism. The proposed architecture exhibits a 28.3% wider stopband with 62.6% smaller footprint compared to a conventional structure. The compactness and bandwidth improvement in the proposed structure is explained with the help of dispersion and circuit analysis. The reconfigurability built into the design using PIN diodes allows stopband switching, dual-band operation and tuning capabilities with the mere use of a single reactive load in its unit cell. To the best of the authors knowledge, it is the first time a reconfigurable MMIC implementation is realized using the proposed structure or even the conventional design. As a guide to design, sensitivity analysis to filter performance is presented for important structure parameters. Switching element parasitics are discussed in two ways: firstly, with the design and measurement of structures with idealized switching conditions and in second, with the circuit and full-wave EM modelling of the finite periodic structure with the actual PIN diodes. The on-chip measurements of the fully reconfigurable filter show excellent agreement with simulations.
Highlights
W ITH the advent of 5G, cognitive radio and ultrawideband systems, demand for the reconfigurable radio frequency (RF) front ends is on the rise [1]–[4]
Filters being an integral part of such RF front ends become more beneficial when they support multiple response types, frequency/bandwidth tuning, band switching, etc. [9], [10]
Various reconfigurable filters reported in the literature demonstrate excellent performance when designed for one or two adaptive features at a time
Summary
W ITH the advent of 5G, cognitive radio and ultrawideband systems, demand for the reconfigurable radio frequency (RF) front ends is on the rise [1]–[4]. In a digitally controlled artificial dielectric (DiCAD) structure in CMOS, this effect is created by the cross-coupling offered by several floating metal strips placed under a differential transmission line [41], [42] One variant of these structures in microstrip arrangement involves using a rectangular patch with a pair of shorting vias in a unit cell to load a microstrip line reactively [20]. It is very important to reduce the overall size of the structure These circuits offer the possibility of creating the reconfigurable EBGs by changing the state of individual unit cell elements. Switching between the two bands is achieved by simultaneously switching all the diodes in a finite periodic structure to ON or OFF states This stopband switching capability of the proposed circuit makes it suitable for the RF front-ends of the half-duplex communications systems.
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