Integrated passive devices (IPD) integration with eWLB (embedded wafer level BGA) for high performance RF applications

The demand for wireless communications is increasing through use of smart phones, 3G handsets wherein high speed and reliable data communication are crucial requirements. Multi-bands networks help to facilitate these at higher range of radio frequencies. In many wireless communications, power amplifiers (PA) are used to increase the amplitude of relatively weak signals. These PAs depend on matching circuits that generally include capacitor and inductors, to match the impedances of the power amplifier to other radio components. The reduction in cost and die size of multi-mode power amplifiers and matching networks in RF functional blocks is highly desired. So they need to be designed with high efficiency and be integrated for optimum performance. eWLB technology provides the solution for multi die integration. It enables small form-factor and good electrical performance using well controlled wafer fab process and fine line width/spacing. In this work, multi-die eWLB has been successfully developed where both PA die and IPD die for impedance matching network have been placed side-by side, thus providing better multi-chip packaging solution with better performance. Simulation, characterization and design work for PA and IPD integration in eWLB packaging are presented in this paper. The developed IPD mainly consists of inductors resistors, and capacitors for target impedance matching with PA. Simulation results show that the optimized IPD design change improves impedance more than 10% to meet the target impedance which helps to achieve the optimum power amplifier output impedance and maximum output power. Modified inductor design tuning shows significant improvement in impedance values of power amplifier and also enables overall good performance of the eWLB packaging. And package level reliability test results are also presented in this paper.