Miniaturized UHF tunable filter using PCB embedding passive technology

Abstract

In this article, PCB embedded UHF tunable filters with different coupling coefficients have been designed, fabricated, characterized, and compared.The relationship between the coupling coefficient and the performance of a filter has been investigated. The proposed filters were fully embedded into multilayered printed circuit board (PCB). They were comprised of high Q spiral stacked inductors, high dielectric SrTiO3 composite MIM capacitors, and varactor diodes. The fabricated UHF tunable filters were operated in the frequency regime ranged from 500 MHz to 900 MHz for TV tuner receivers. The filter with a coupling coefficient of 0.26 exhibited insertion loss of approximately −2 dB, return loss of below −10 dB, and tuning range of 56.3%. In our knowledge, the fabricated UHF tunable filter was first embedded into the organic packaging substrate and the smallest one in the previously reported devices, which had compact size/volume of 3.4 × 4.4 × 0.6 mm3. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1768–1771, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25306