Research On Three-Dimensional Microwave Passive Devices Design Based On Through-Silicon-Vias

As wireless communication technology advances,on-chip integrated passive components have become more widely researched and applied.However,most of these components use planar structures that are hard to miniaturize effectively.As a result,the area occupied by passive components in monolithic microwave integrated circuits(MMIC)keeps increasing over time.Therefore,the miniaturization of passive components is essential for enhancing microwave system performance.Three-dimensional(3-D)microwave passive devices based on 3-D packaging technologies such as through-silicon via(TSV)and redistribution layer(RDL),compared with traditional planar passive components,not only have higher integration density,but also have stronger compatibility with three-dimensional integrated circuits(3-D IC),making them a promising breakthrough for solving bottlenecks in microwave systems.This article focuses on TSV-based 3-D passive component technology,expounds its working principle and technical advantages,and presents a systematic research work around core scientific issues such as equivalent circuit modeling,3-D structure conversion,and design methodology.Passive inductors,balun converters,and directional couplers are used as typical passive component types.The main research results are as follows:1.This paper develops a physics-based equivalent circuit model of TSV-based inductors that enables high-precision computation of the high-frequency characteristics.The model uses frequency-independent lumped elements and aΠ-type circuit structure,which can effectively reflect the frequency response of various parasitic effects inside 3-D inductors.By adopting an equivalent method that combines a double-step circuit and a mirror circuit,the model can more accurately equivalent the current distribution inside TSV and RDL,as well as the distinct effects of skin effect and proximity effect on them.Meanwhile,the modeling method fully considered the influence of factors such as feedforward capacitance,oxide liner capacitance,and substrate parasitic effect.By comparing experimental measurements with 3-5 turns TSV-based inductors fabricated on 300μm high-resistance silicon substrates,the model was verified to accurately predict the trend of key characteristics with frequency.The model prediction error is less than 1.5%for inductance at 1 GHz,less than 3.5%for maximum quality factor,and less than 4%for self-resonant frequency.Furthermore,electromagnetic(EM)simulations with floating values of TSV radius,RDL width,pitch and substrate height verify that the model has good scalability.2.This paper proposes a TSV-based Marchand balun and its design methodology for monolithic and 3-D integration.By utilizing 3-D packaging process including TSV and RDL,the original planar coupling path is converted into a meander coupling path that is vertically embedded in the substrate.The proposed structure can effectively reduce on-chip area while maintaining good balance characteristic.The 3-D structure can be flexibly integrated with 3-D ICs to directly realize signal conversion between different stacking tiers.An equivalent circuit model based on TSV-to-TSV coupling channel and coupled transmission line model has been established for initial estimation before EM optimization.In addition,the specific design and process flow is proposed to meet the structural particularity and different application scenes.To verify the structure and design method,a design case is analyzed and EM simulated with the V-band dipole antenna feeding network as the target application.The EM simulation results show that the design can work at 43-82GHz with the amplitude imbalance of less than 0.3 d B and the phase imbalance of less than1.3°,which meets the requirements of the balanced feeding purpose.It only costs a 0.084λ_g×0.009λ_gfootprint,which is far lower than that of conventional planar types.3.This paper establishes a design strategy based on TSV insertion and Neuro-transfer function(Neuro-TF)modeling to achieve miniaturization of coupled-line directional couplers.By embedding coupled TSV pairs inside the substrate,planar directional couplers can be transformed into 3-D structures with smaller footprint.Two insertion schemes with regular and coaxial TSVs are applied respectively,according to different design requirements and constraints.In addition,a design flow is proposed to achieve the initial parameters of TSV insertion for various application scenarios.The flow can estimate the number of required TSV pairs according to the area reduction target.To reduce the dependence on EM simulation and make the method applicable to various types of couplers,this paper adopts the Neuro-TF modeling method to optimize the parameters after preliminary design.This paper also analyzes the compatibility between TSV insertion and Neuro-TF method to further improve the miniaturization strategy.The approach has been validated by two design cases through EM simulations.The results indicate that the proposed method can achieve area reduction target in a short cycle,and can quickly evaluate the impact of parameter changes on the performance of directional coupler.