Compensating Method of Equivalent Current Sources of LSI-Core Macromodel Considering Voltage Fluctuations in On-Chip Power Distribution Network

Electro-magnetic compatibility (EMC) macromodels of a large-scale integrated (LSI) circuit core have been proposed to predict conducted RF emission and power integrity issues not only on a printed circuit board but also inside an LSI. They are equivalent circuit models that consist of lumped element impedance blocks of an LSI-core and equivalent current sources expressing internal switching activities. In conventional macromodeling, equivalent current sources have been extracted under ideal power supply conditions, i.e., with constant supply voltage. However, there exists transient supply voltage fluctuations in an actual on-chip power distribution network (PDN), and the operating current and its equivalent current sources are expected to vary with such fluctuations. Such issues with transient supply voltage fluctuations have not been extensively investigated. We propose a method of compensating the equivalent current sources of a macromodel by introducing amplitude and time correction factors, taking into account the voltage fluctuations in an on-chip PDN.

I. Introduction

High density and high speed are becoming increasingly important for large-scale integrated (LSI) circuits to achieve higher functionality. To cope with power consumption and heat issues, the supply voltage of LSIs decreased continuously. Therefore, power integrity (PI) issues due to high-speed switching are becoming more serious. In particular, the simultaneous switching noise generated by a large amount of gate switching is one of the main factors causing large voltage fluctuations in on-chip power distribution networks (PDNs).