Component packaging footprint: Surprising element of high speed filter design

Abstract

It is very intriguing to design passive filters in a very small package, in the frequency domain of 10 GHz and above. Modeling the device footprint and correctly incorporate the model in the design work to design passive filter is key to successfully manufacture surface mount filter components that perform as expected, once they are mounted to the printed circuit board. This requires accurate correlation to the filter model and the measured first article component. In this work we studied footprint and it's influence in the final product. We developed filter design procedure using simulation software. We considered the impact of the parasitic of the input signal lines, printed circuit board's footprint parasitic, and filter's signal launch pad loss. We discussed an efficient way to design low pass passive filters in Ball Grid Array package; we optimized the design flow to manufacture filters. Then we designed and manufactured 12 GHz 9 th order absorptive low pass Bessel filter, whose size is 2.0 mm X 7.1 mm. We compared the measured data of the fabricated filter with the simulation results. We discussed the use of Coaxial Measurement Modules, which contains the filter with optimized design footprint.