Electrical design optimization and characterization in Cell Broadband Engine package

Cell Broadband Engine is a microprocessor that has very high processing performance and very high speed I/O to communicate with other devices such as system LSI and memory chips. Design optimization with statistical analysis was carried out. DOE matrix was made with dimension of signal traces and dielectric constant of the insulator in the package substrate. After major factors were detected, random sampling was done to make sure that the distribution of characteristic impedance of signal traces is within the specification. Passive characterization was carried out with test vehicle. Insertion loss and characteristic impedance is dependent on both temperature and water absorption. These environmental factors need to be taken into account when the design rule is determined. After design rule is fixed, circuit simulation for whole signal channel was carried out with considering impedance tolerance in both the package and the printed circuit board. DOE matrix was made and analyzed to determine the major factors on mid-frequency and low-frequency noise in power distribution. Inductance of package substrate and decoupling capacitor are the major effect on the mid-frequency noise, and capacitance of on-module and on-PCB affect low frequency noise. The effect of on-chip parameters was also evaluated. Several types of capacitors were characterized to measure their parasitic parameters.