Development of an integrated LTCC Bluetooth module

In this paper, a system-on-package (SoP) approach for Bluetooth system modules using low temperature co-fired ceramic (LTCC) substrate technology is presented. The proposed Bluetooth module is overall 12mm by 12mm in size, with integration of two originally proposed components, a balanced-to-unbalanced filter and an antenna, as well as other passive circuitries. The embedded balanced-to-unbalanced filter, which is derived from the basic center-tapped transformer circuit, works simultaneously as a balun and a bandpass filter, thus leads to a significant amount of size reduction for the overall module. Likewise, comparing with the usual half-wavelength printed antennas, our proposed antenna is only one-tenth of wavelength in size without sacrificing of efficiency. Consequently, couplings among various embedded components of this highly integrated module are crucial to its performance and the resulting effects are discussed. A fully functional prototype has been successfully fabricated, showing a promising solution for Bluetooth applications.