LTCC bandpass filter for Bluetooth™ application with dual transmission zeros

A LTCC band-pass filter with dual transmission zeros for Bluetoothtrade application was presented. With the classic network synthesis method, a lumped LC filter was educed and then transformed to physical prototype with LTCC process. This prototype was refined with DOE method, and was implemented in Zhejiang Zhengyuan Electric Co. Ltd. The measured insertion loss is less than 1.8 dB at 2400 MHz, and two transmission zeros are obtained at 1.7 and 7.1 GHz, respectively. They result in 40-45 dB for lower stop band suppression and 45-50 dB for higher stop band reduction. The experimental data agree very well with the 3-D simulation.