Zhaoqing Chen

A fast simulation method for single and coupled lossy lines with frequency-dependent parameters based on triangle impulse responses

This paper describes a fast simulation method for single and coupled lossy transmission lines based on triangle impulse responses. The method can be applied to simulating systems consisting of large numbers of lossy transmission lines with frequency-dependent parameters in high-speed IC package design.

Linear circuit model combination for coupled noise simulation by using directional junction

A circuit level linear model combination technique using directional junction model is proposed. The method allows direct usage of two or more existing packaging component circuit models which have some shared coverages to form a new model with a larger coverage than any individual one. The accuracy of the method is compared to the reference models. This method is useful for the applications of multiaggressor single-victim coupled noise simulation.

Crosstalk Superposition of Multiple Aggressors in Electronic Package System Pre-PD Signal Integrity Simulations

A new method of crosstalk superposition of multiple aggressors is proposed to make the system pre-PD signal integrity simulations simpler, easier, and faster. The new method uses a single virtual aggressor to represent multiple aggressors based on the concept of directional junction. The accuracy of this method is verified by comparing the simulated waveforms with those by conventional method in both single ended and differential applications. This method is for general-purpose circuit/system simulation tools and can be applied to multi-coupled transmission line models as well as component quasi-static and fullwave models

Differential twinax cable modeling by measured 4-port S-parameters

A method for making SPICE circuit model of differential twinax cable from measured 4-port S-parameters is proposed. Ideal transmission lines are used in the middle of the model to represent the major part of the cable delay. Commercial SPICE model generator based on S-parameters can be used for the rest parts of the model. The circuit models have good correlation with the original measured frequency-domain responses and can be used in any SPICE-like transient circuit simulation tools.

A lumped/discrete port de-embedding method by port connection error-cancelling network in full-wave electromagnetic modeling of 3D integration and packaging with vertical interconnects

In this paper, a lumped/discrete port de-embedding method by port connection error-cancelling network is proposed for full-wave modeling interconnect and packaging components with bump/pin array interfaces in 3D integration as well as conventional packaging systems. This method is based on the S-parameter matrix operation. Three calibration structures are simulated for extraction of the error-cancelling network. This error-cancelling network is inserted into the physical port connection interface in system SI simulation to cancel the port connection error caused by the port parasitic parameters and the uncertainty in port voltage and current definitions. Theoretically this method is a wide-band approach valid on every frequency point included in the S-parameter model. This approach is verified by two application examples with signal, power, and ground ports for power-aware SI applications including a 20-port 9-chip stack connected by TSVs, a 20-port module-board-module structure, and the third example of a 36-signal-port printed circuit board via array for conventional SI applications. The connection error of cascaded physical networks after de-embedding by inserting the proposed error-cancelling network at the physical connection location is much smaller than the one without de-embedding.

Time-domain scattering method using triangle impulse responses for modeling electronic packaging components

This paper describes a time-domain scattering method using triangle impulse response for modeling electronic packaging components such as connectors and vias. The method provides a direct data interface for linear component models to time-domain EM/circuit simulation tools.

A new approach to deriving packaging system statistical eye diagram based on parallel non-linear transient simulations using multiple short signal bit patterns

The eye diagram simulation is very important for checking the signal quality of channels in electronic packaging systems. Most existing simulation tools for creating eye diagram are based on convolution using a single-step response of the channel and require that the I/O devices are modeled as linear time-invariant circuits. However, I/O devices do contain nonlinear elements and some applications have strongly nonlinear I/O devices. We need an alternative eye diagram simulation methodology to simulate these non-linear applications. In this paper, we propose a new approach to deriving the packaging system statistical eye diagram based on nonlinear transient simulations. This is achieved by taking advantage of the ready availability of multi-core networked computers and breaking the bit patterns into many short signal bit patterns and running these simulations in parallel. This can be done with any transient circuit simulator. This approach gives a practical way to overcome the time required to run the more compute intensive non-linear transient simulations. A major advantage of this approach is the capability to include the nonlinear effect of the actual I/O devices. The statistical eye diagram and the BERT scan eye diagram by the proposed approach includes the non-ideal channel characteristics including inter-symbol interference (ISI), the crosstalk from nearby aggressor channels, the random jitter, and duty cycle distortion. The proposed approach is illustrated with the simulation an actual channel from an IBM server. The statistical eye diagram is compared between this approach and the commonly used linear convolution methods.

Constructing 3D package component broadband electrical models with correct DC values

Accurate channel simulations of package interconnections require passive and causal models that faithfully represent the full frequency response from tens of gigahertz to DC. In this paper, we propose and test a method to create accurate models extending to DC while retaining passivity and causality. The model derived by this method is suitable for transient simulations of packaging interconnect systems.

Predictions of the Worst-Case Crosstalk Including ISI Effect and the Worst-Case Eye Opening Including Crosstalk Effect for Electronic Packaging System Design

New methods for predicting the worst-case crosstalk caused by intersymbol interference and the worst-case eye opening including crosstalk effect are proposed. The new method for predicting the worst-case crosstalk is based on simulated or measured crosstalk caused by a single bit aggressor signal. By using the derived worst-case crosstalk and the no-crosstalk worst-case eye opening, we can get worst-case eye opening including crosstalk effect. The proposed methods are exactly valid for packaging component and system with linear I/O devices as the signal source and load. They can also be extended to some nonlinear I/O cases with approximations.

A comparison of performance potentials of single ended vs. differential signaling

The performance comparison of single ended and differential signaling of 10-40Gb/s is documented here with an interconnect distance of 12-20 mm on a high loss first level packaging structure. The comparison was based on eye diagrams by circuit simulators using multi-coupled transmission line models with frequency-dependent RLGC parameters.