Lattice‐type balun with enhanced phase characteristic based on organic system on a package technology

In this article, lattice-type LC balanced-to-unbalanced (balun) embedded into a multilayered organic package substrate have been designed, fabricated, and characterized for low cost and small size WLAN and Bluetooth applications. To minimize the phase error of the embedded baluns, LC resonator was utilized instead of shunt capacitor used at conventional lattice-type balun, furthermore, the quality factors and packaging efficiencies of embedded inductors are maximized by using vertically stacked circular geometry. It has the insertion loss of 0.7 dB, return loss of 21 dB, phase imbalance of 5°, and frequency band width ranged from 2.3 to 2.55 GHz. The fabricated balun was significantly reduced in size and volume by using the vertically stacked spiral inductors and MIM capacitors with BTO high DK film. It has a size of 2.7 ×2.5 ×0.66 mm (height). It is promising for various RF system on a package (SOP) products with multi functionalities, small size, and low cost. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 399–402, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24041