Research On Silicon-based Passive Integration Technology In System-in-package

The miniaturization and high performance of passive components in system-level packages are the key to the miniaturization of SiPs.Silica-based passive integrated(IPD)technologies have the advantages of small size,good consistency,and high integration and reliability,making them a system level.The preferred solution for passive components in the package.Filter integration is one of the primary issues,but due to the low quality factor of the inductor on silicon,the integrated filter performance is limited,especially in narrow-band applications.In view of this situation,based on an in-depth understanding of the IPD process structure and characteristics of electrical parameters,this paper combines the circuit design and process to develop an integrated design study of silicon-based band-pass filters,which mainly includes the following three aspects:1.Using the three-dimensional electromagnetic simulation software,a parametric model of planar spiral inductor structure was established.The influence of the geometric parameters of the inductor such as the number of turns,the inner diameter,the line width,and the space between lines on the electrical characteristics of the inductor was analyzed through simulations,and the methods for the improvement of the inductor Q factor such as the cut angle and the multiple current paths was verified through simulation.Then,based on a deep understanding of the relationship between the structure formed by silicon-based IPD process and electrical properties,a novel and compact four-inductor mutual-coupling structure was proposed,and the physical layout basis for designing a band-pass filter was established.2.For the problem that it is difficult to obtain the frequency-dependent coupling matrix,an optimization method based on the generalized eigenvalues of the matrix is proposed.The coupling matrix of the frequency-dependent coupling band-pass filter is solved by this method.The coupling matrix structure and the array element values correspond to the filter topology and the coupling coefficient between the resonant elements,which establishes the structural basis for designing a frequency-change cross-coupling filter.3.The distribution characteristics of transmission zero formed by frequency-dependent coupling are analyzed,and the lumped circuits of second-order frequency-dependent coupling filter were summarized.Based on the proposed four-inductor mutual coupling structure and the frequency-dependent coupling matrix,two compact bandpass filters were designed by using the proposed bandpass filter design method of lumped-resonator,distributed mutual inductor coupling,combined with three-dimensional electromagnetic simulation and full circuit optimization.Their size is only 1.5 x 1mm2.The filters were then taped and the samples tested.Their insertion loss in the passband was low,and their rejection outside the passband was high.The test results show that this method is suitable for narrowband filters on silicon.And the test is in line with the simulation curve,indicating that the established silicon-based IPD simulation model is accurate.