Showing papers by "Jun Fan published in 2009"
TL;DR: In this paper, an analytical model for vias and traces is presented for simulation of multilayer interconnects at the package and printed circuit board levels, which can be applied to efficiently simulate a wide range of structures.
Abstract: Analytical models for vias and traces are presented for simulation of multilayer interconnects at the package and printed circuit board levels. Vias are modeled using an analytical formulation for the parallel-plate impedance and capacitive elements, whereas the trace-via transitions are described by modal decomposition. It is shown that the models can be applied to efficiently simulate a wide range of structures. Different scenarios are analyzed including thru-hole and buried vias, power vias, and coupled traces routed into different layers. By virtue of the modal decomposition, the proposed method is general enough to handle structures with mixed reference planes. For the first time, these models have been validated against full-wave methods and measurements up to 40 GHz. An improvement on the computation speed of at least two orders of magnitude has been observed with respect to full-wave simulations.
153 citations
09 Oct 2009
TL;DR: In this article, the authors improved the conventional lumped circuit model by introducing a model for the inductance of each via that is frequency-dependent, which is obtained from a rigorous cavity model formulation.
Abstract: In power distribution network (PDN) modeling, interconnection inductance can play a critical role. It often determines the effectiveness of a component, such as a decoupling capacitor. This paper studies a typical one-plane-pair PDN structure with parallel power and ground planes and vertical vias in between. This work improves the conventional lumped circuit model for the PDN by introducing a model for the inductance of each via that is frequency-dependent. This frequency dependency is obtained from a rigorous cavity model formulation. The improved lumped circuit model is validated with the cavity model and the HFSS full-wave model. Further, the frequency-dependent mutual inductance between two vias can have either a positive or a negative value depending on via locations in the PDN structure, which is an interesting property that has not been reported.
35 citations
09 Oct 2009
TL;DR: In this article, a closed-form expression for the impedance of an infinitely large parallel plane pair is presented, which is applicable to practical printed circuit board (PCB) design problems.
Abstract: In this paper, a closed-form expression for the impedance of an infinitely large parallel plane pair is presented. It is applicable to practical printed circuit board (PCB) design problems where there are multiple shorting vias around the signal vias of interest. With the presence of multiple shorting vias, reflections from the plane pair edges can be neglected since the shorting vias prevent the electromagnetic energy from leaking away from the local cavity around the signal vias. The self and transfer impedance expressions can be obtained using the expansion of cylindrical waves. The impedances calculated from both the rectangular cavity model and the infinitely large plane pair model for several design examples are compared to demonstrate the effectiveness of the infinite plane pair approximation.
16 citations
09 Oct 2009
TL;DR: In this article, the performance of differential signal via structures in multi-layer printed circuit boards (PCBs) and packages is studied using an equivalent coupled multi-conductor transmission-line model.
Abstract: Differential signal via structures in multi-layer printed circuit boards (PCBs) and packages are studied using an equivalent coupled multi-conductor transmission-line model. Thus, easy-to-understand transmission-line concepts, such as mixed-mode characteristic impedances and propagation constants, can be used to characterize the performance of differential signal via structures in a signal path. The closed-form expressions of per-unit-length parameters in the equivalent coupled multi-conductor transmission-line model are derived based on a physics-based via circuit model with parallel-plane impedances and via-plate capacitances. Mode conversions are discussed for different via structures. Effects of geometrical parameters on equivalent differential via impedances are studied in the paper as well. The proposed method provides a straightforward approach to design differential via structures for better signal integrity.
15 citations
09 Oct 2009
TL;DR: In this article, the mixed-mode input impedance of differential vias in typical multilayer structures is derived, and the input impedance concept is used to achieve impedance matching at the via and trace connections.
Abstract: In multilayer printed circuit boards (PCBs), vias are commonly used to connect traces on different signal layers. This paper derives the mixed-mode input impedance of differential vias in typical multilayer structures, and proposes to use the input impedance concept to achieve impedance matching at the via and trace connections. Effects of several geometrical parameters on the input impedance of differential vias have also been studied in this paper. This method can be used to optimize via structures in PCB design processes for smooth via-trace transitions.
14 citations
09 Oct 2009
TL;DR: In this paper, a multi-step crosstalk evaluation procedure is proposed based on the study for PCB layout-design verifications for high-speed digital circuits, where a physics-based equivalent circuit model, including parallel plane pair thickness, layer count in printed circuit board (PCB) stackup, ground via patterns, and parallel plane pairs dimensions, is investigated.
Abstract: Crosstalk among vias is a critical problem in high-speed digital circuits, deteriorating signal quality and increasing jitter, especially when circuit density is high. Underlying mechanism of crosstalk among vias is investigated in this paper. Using a physics-based equivalent circuit model, crosstalk as a function of various geometrical parameters, including parallel plane pair thickness, layer count in printed circuit board (PCB) stackup, ground via patterns, and parallel plane pair dimensions, has been investigated. A multi-step crosstalk evaluation procedure is proposed based on the study for PCB layout-design verifications.
12 citations
17 Nov 2009
TL;DR: In this paper, a method to calculate equivalent inductances of multiple vias in arrays has been proposed, which has been applied to the modeling of a hierarchical power bus and validated by measurements.
Abstract: A method to calculate equivalent inductances of multiple vias in arrays has been proposed. The method has been applied to the modeling of a hierarchical power bus and validated by measurements. It is accurate at the frequencies lower than the cavity resonant frequencies.
10 citations
TL;DR: In this article, an integral approximation method is proposed to extract the via-plate capacitance of an eccentric via in the via hole (anti-pad), which is used as a benchmark to validate the method.
Abstract: An integral approximation method is proposed to extract the via-plate capacitance of an eccentric via in the via hole (anti-pad). An analytical formula is derived for the coaxial capacitance part, which is used as a benchmark to validate the integral approximation method. Furthermore, numerical simulations are also used to validate the method. It is shown that small eccentricity results in only a few percentage increase of the via-plate capacitance, which is helpful in specifying the manufacturing tolerance of via designs.
8 citations
09 Oct 2009
TL;DR: Four via modeling methods including physics-based circuit model, equivalent transmission line model, multiple scattering model, and full wave model are compared and validated by the approach proposed in this paper to illustrate the effectiveness of different via modeling techniques.
Abstract: A new approach is proposed in this paper to validate different uncertain approaches without knowing a standard reference by applying the Feature Selective Validation (FSV) technique. New reference is established by the weighted average of the various approaches. Four via modeling methods including physics-based circuit model, equivalent transmission line model, multiple scattering model, and full wave model are compared and validated by the approach proposed in this paper to illustrate the effectiveness of different via modeling techniques.
6 citations
01 Dec 2009
TL;DR: In this paper, the current distribution along via barrel and pad is obtained by the Green's function of a generalized coaxial cavity for a magnetic frill current, and an analytical formula for both the barrel-plate and pad-plate capacitances are derived by observing the current difference along the via barrels and pad.
Abstract: The current distribution along via barrel and pad is obtained by the Green's function of a generalized coaxial cavity for a magnetic frill current. An analytical formula for both the barrel-plate and pad-plate capacitances are derived by observing the current difference along the via barrel and pad. Finite difference method has been used to validate the formula derived here. Analytical formula presented facilitates the implementation of the physics-based via circuit model in practical via designs for printed circuit boards and packages. The impact of various via geometric parameters on the parasitic capacitances has been investigated.
4 citations
13 Feb 2009
TL;DR: In this article, the Cavity Model (where facing portions of power bus are considered electromagnetic resonant cavities) can be used to study the generation and propagation of noise given a real-world board's layout, one of the primary requirements for the application of this technique is the geometrical identification of all the cavities and their connectivity.
Abstract: The analysis and the design of the Power Delivery Network (PDN) is crucial in the real world of high-speed and high-performance on-board systems In this context, the Cavity Model (where facing portions of power bus are considered electromagnetic resonant cavities) can be used to study the generation and propagation of noise Given a real-world board's layout, one of the primary requirements for the application of this technique is the geometrical identification of all the cavities and their connectivity This paper is focused on the fully automatic generation of this geometrical dataset as part of an integrated tool for the analysis and design of PDN
01 Dec 2009
TL;DR: In this paper, a new definition of power-bus impedance in terms of cylindrical waves is proposed and the equivalence of the new definition and the conventional one is proved in the case of electrically small ports.
Abstract: The drawbacks of conventional power-bus impedance, defined as an average Green's function integration over port areas, are discussed A new definition is proposed in terms of cylindrical waves The equivalence of the new definition and the conventional one is proved in the case of electrically small ports Addition theorems of cylindrical waves are used to derive an analytical expression of power-bus impedance between ports in a circular plate pair with perfectly electric/magnetic conductor (PEC/PMC) boundaries as well as non-reflective perfectly matched layer (PML) for infinite plate pair Numerical method has been used to validate the analytical expression derived
17 Nov 2009
TL;DR: In this paper, a perforated disk resonator with non-plated holes was used to investigate the BIE and effective dielectric medium approaches for common via array structures.
Abstract: In high-speed printed circuit board (PCB) designs, vias play a critical role in determining signal and power integrity. This paper uses disk resonators to investigate modeling approaches for common via array structures. Boundary integral equation (BIE) and effective dielectric medium approaches are used for a perforated disk resonator with non-plated holes, using dielectric properties derived from a solid disk resonator study. Both approaches are compared and validated with measurements.