Mina Farhan

Overlapping Partitioning Techniques for Simulation of Strongly Coupled Distributed Interconnects

The large number of interconnects in high-speed circuits is a major bottleneck for fast simulation of such circuits. Recently, waveform relaxation methods based on transverse partitioning (WR-TP) were proposed to address this issue. It was shown that the complexity of WR-TP grows only linearly with the number of lines. However, as the coupling between the lines becomes stronger, the WR-TP algorithm either fails to converge or the number of iterations required for convergence increases. In this paper, an overlapping partitioning method for WR-TP is presented, which overcomes the effect of strong coupling between the lines. Numerical examples are presented which demonstrate the accuracy and efficiency of the proposed method for tightly coupled lines.

Fast Simulation of Microwave Circuits With Nonlinear Terminations Using High-Order Stable Methods

This paper describes a new method for transient simulation, using high-order stable methods, of microwave structures modeled using a large number of lumped components. The target of the proposed technique is circuit-based simulation of the large linear circuits that arise from full-wave modeling of distributed structures, such as transmission lines and microstrip elements, along with the terminating nonlinear devices. In this case, the cost of the solution of the linear system typically dominates the computational effort. The proposed method takes advantage of the special structure of the block matrices in these applications to reduce the computational cost significantly. The core of the proposed algorithm is based on the idea of “node tearing” to separate the large linear sub-circuits from the nonlinear devices. This idea faciliates handling the linear sub-circuits using a better matrix factorization technique, resulting in faster simulations compared to classical techniques.

New Method for Fast Transient Simulation of Large Linear Circuits Using High-Order Stable Methods

A new algorithm based on A -stable and L-stable high-order time-domain integration methods is presented for the simulation of large linear circuits such as those occurring in modeling chip interconnects and packaging structures. The proposed method takes advantage of the special structure of the mathematical formulation of circuits encountered in these applications to reduce the computational cost significantly. Several circuit examples are presented to demonstrate the speedup achieved by the proposed algorithm.

Efficient transient simulation of transmission lines and distributed circuits using high-order stable methods

This paper describes an efficient technique for simulating large linear circuits in the time-domain using high-order stable methods. The target area of the proposed technique is in circuit-based simulation of the large linear circuits that arise from full-wave modeling of distributed passive structures such as transmission-lines and microstrip elements. In these applications, the cost of linear system solution typically dominates the computational effort at each time-step. The proposed method takes advantage of the special structure of the block matrices in these applications to reduce the computational cost significantly.

High-order envelope following method for accurate transient analysis of almost periodic electrical circuits

A novel Envelope Following (EF) method is presented for fast and accurate transient simulation of microwave and RF circuits with almost-periodic responses. Targeted circuits contain high-frequency components whose amplitudes vary slowly. The proposed high-order EF method is based on a stable and high-order Obreshkov formula (ObF). Use of high-order formula allows accurate and fast analysis while keeping the same accuracy as the conventional low-order integration methods and is validated by the presented numerical example.

Parallel Simulation of Large Linear Circuits With Nonlinear Terminations Using High-Order Stable Methods

To meet the growing demand for efficient circuit simulation tools, Obreshkov formula (ObF)-based high-order integration methods were recently proposed. However, one of the challenges in this method is the growing computational cost of the solution at a particular time point with the increasing orders of the ObF. To address this issue and target high-speed circuits with large linear blocks and nonlinear loads, a new parallel framework is proposed in this paper to minimize the CPU time associated with the solution at any time point. For this purpose, recently identified special properties of the resulting circuit matrices and the node-tearing principles are exploited, while developing an efficient parallel simulation framework. Numerical examples are presented to demonstrate the validity and efficiency of the proposed parallel method.

High order Envelope Following method for parallel simulation of Power Converter circuits

Transient analysis of Switching Power Converter (SPC) circuits is a computationally expensive task. This high expense arises from the fact that these circuits are driven by a clock with a period that is very small compared to the time interval the designer is typically interested in. Envelope-Following (EF) technique has been recently proposed in the literature for efficient time-domain simulation of SPC circuits. In this paper, a parallel high-order EF method, which is based on Obreshkov-Formula, is presented for analysis of SPC circuits. A numerical example is presented to demonstrate the efficiency and scalability of the proposed method on parallel platforms.

High Order and A-Stable Envelope Following Method for Transient Simulations of Oscillatory Circuits

A new enveloped following (EF) method based on high-order Obreshkov integration formula is presented. The new method is suitable for transient analysis of highly oscillatory circuits with widely separated time-scales. In addition, the proposed algorithm is capable of producing high-order numerically stable approximation of the transient response. The use of high-order formulas leads to a significant reduction in the computational time compared to low-order EF methods because it allows taking large steps in time while keeping the same accuracy.

Fast Transient Analysis of Tightly Coupled Interconnects via Overlapping Partitioning and Model-Order Reduction

The presence of a large number of interconnects in high-speed circuits is a major bottleneck for the fast simulation of such circuits. Iterative approaches, such as waveform relaxation (WR) methods, were proposed to allow fast analysis of highspeed interconnects. In the case of strong coupling between the lines, overlapping partitioning (OP) techniques were proposed to speedup the convergence rate of WR methods, wherein the methods, the Multi Transimission Lines are partitioned such that the strongly coupled lines are in the same subcircuit. However, in the case of increasing the number of overlapping lines, the simulation efficiency can suffer due to the increasing size of each subcircuit. In this paper, an accelerated OP method is proposed. The proposed method uses model-order reduction techniques (MOR) to obtain a reduced model for the partitioned subcircuits allowing for fast simulation in each iteration, thus providing a speedup in the overall simulation time. Also, a new method is presented for efficient updating of relaxation sources while using MOR.

Waveform relaxation and overlapping partitioning techniques for tightly coupled interconnects

The large number of interconnects in high-speed circuits is a major bottleneck for fast simulation of such circuits. Recently, waveform relaxation methods based on transverse partitioning (WR-TP) were proposed to address this issue. It was shown that the complexity of WR-TP grows only linearly with the number of lines. However, as the coupling between the lines becomes stronger, the WR-TP algorithm either fails to converge or the number of iterations required for convergence increases. In this paper, an overlapping partitioning method for WR-TP is presented, which minimizes the number of iterations in the presence of strong coupling between the lines.