Ultracompact UHF Tunable Filter Embedded Into Multilayered Organic Packaging Substrate

In this paper, we developed a new ultracompact ultrahigh frequency tunable band-pass filter embedded into multilayered organic packaging substrate with high dielectric composite film. For embedding the tunable filter circuit into the packaging substrate, it was modified by using a scalable lumped circuit model instead of using magnetically coupled resonant circuit. Since most of the conventional TV receiver tuners utilize magnetically coupled circuit, which is formed of several passive components and air core inductors assembled and controlled manually, there are several problems such as large size, difficulty in tuning, and high cost. The embedded tunable filter was optimally designed to obtain high performances by using high Q spiral stacked inductors, high dielectric SrTiO₃ composite metal-insulator-metal capacitors, and surface mounted varactor diodes. It exhibited low insertion loss of approximately -2 dB, return less than -10 dB, large tuning range of 56.3% and tunable frequency ranged from 500 to 900 MHz. It had extremely compact size and volume of 3.4 × 4.4 × 0.6 mm³, which was the smallest one in the reported tunable filters for TV tuner receivers.