Fast Analysis of Power/Ground Networks via Circuit Reduction

This paper presents an efficient algorithm for reducing RLC power/ground network complexities by exploitation of the regularities in the power/ground networks. The new method first builds the equivalent models for many series RLC-current chains based on their Norton＇s form companion models in the original networks,and then the precondition conjugate gradient based iterative method is used to solve the reduced networks,which are symmetric positive definite. The solutions of the original networks are then back solved from those of the reduced networks.Experimental results show that the complexities of reduced networks are typically significantly smaller than those of the original circuits, which makes the new algorithm extremely fast. For instance, power/ground networks with more than one million branches can be solved in a few minutes on modern Sun workstations.

An Integrated Tool for Power/Ground Network Design, Optimization,and Verification for Cell Based VLSIs

A CAD tool based on a group of efficient algorithms to verify,design,and optimize power/ground networks for standard cell model is presented.Nonlinear programming techniques,branch and bound algorithms and incomplete Cholesky decomposition conjugate gradient method (ICCG) are the three main parts of our work.Users can choose nonlinear programming method or branch and bound algorithm to satisfy their different requirements of precision and speed.The experimental results prove that the algorithms can run very fast with lower wiring resources consumption.As a result,the CAD tool based on these algorithms is able to cope with large-scale circuits.

Analysis on the Irregular and Asymmetrical Power/Ground Structure by PEEC Modeling

In order to provide some reference for the design of the power/ground system, a complicated power/ground system in time and frequency domains was analyzed, which is based on PEEC (Partial Element Equivalent Circuit). According to the actual requirements, characteristics of some common power/ground structures in time and frequency domains, such as SSN (Simultaneous Switching Noise), are obtained for the future research. The results show the first resonance point is changed with the structure of the power/ground networks.

Design point analysis of two-shaft gas turbine engines topped by four-port wave rotors for power generation systems

Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves.In ground power plants,they can be used as topping devices to existing gas turbines aiming to improve their performance characteristics.A four-port wave rotor is an attractive configuration to be integrated into the gas generator of a two-shaft gas turbine,typical for power generation and propulsion systems,by slightly modifying the architecture of existing engines.In particular,in the present article the wave rotor-topped engine utilizes the same compressor,combustion chamber and turbine inlet temperature of the baseline engine.Cycle analysis for two-shaft gas turbine engines topped with four-port wave rotors is studied and their performance at design point is compared to the performance of the baseline engines accordingly.It is concluded that important benefits are obtained with respect to the ones of the baseline engines in terms of specific work and specific fuel consumption.Furthermore calculations by varying the pressure ratio within the wave rotor and the pressure losses in the ducts connecting the wave rotor to the engine’s components indicate the effect on performance,for engines with different compressor pressure ratios and turbine inlet temperatures.

In-package P/G planes analysis and optimization based on transmission matrix method

Power integrity (PI) has become a limiting factor for the chip's overall performance, and how to place in-package decoupling capacitors to improve a chip's PI performance has become a hot issue. In this paper, we propose an improved trans- mission matrix method (TMM) for fast decoupling capacitance allocation. An irregular grid partition mechanism is proposed, which helps speed up the impedance computation and complies better with the irregular power/ground (P/G) plane or planes with many vias and decoupling capacitors. Furthermore, we also ameliorate the computation procedure of the impedance matrix whenever decoupling capacitors are inserted or removed at specific ports. With the fast computation of impedance change, in-package decoupling capacitor allocation is done with an efficient change based method in the frequency domain. Experimental results show that our approach can gain about 5× speedup compared with a general TMM, and is efficient in restraining the noise on the P/G plane.

Modeling and Analysis of Mesh Tree Hybrid Power／Ground Networks with Multiple Voltage Supply in Time Domain

This paper proposes a novel algorithm, which can be used to model and analyzemesh tree hybrid power/ground distribution networks with multiple voltage supply in time domain.Not only this algorithm enhances common method''s ability on analysis of power/ground network withirregular topology, but also very high accuracy it keeps. The accuracy and stability of thisalgorithm is proved using strict math method in this paper. Also, the usage of both preconditiontechnique based on Incomplete Choleskey Decomposition and fast variable elimination technique hasimproved the algorithm''s efficiency a lot. Experimental results show that it can finish the analysisof power/ground network with enormous, size within very short time. Also, this algorithm can beapplied to analyze the clock network, bus network, and signal network without buffer under highworking frequency because of the independence of the topology.