Properties of Digital Switching Currents in Fully CMOS Combinational Logic

• Published in: IEEE transactions on very large scale integration (VLSI) systems 2010-12, Vol.18 (12), p.1625-1638
• Main Authors: Boselli, G, Trucco, G, Liberali, V
• Format: Article
• Language: English
• Subjects: Applied sciences; Circuit properties; CMOS digital integrated circuits; CMOS logic circuits; Combinational circuits; Design. Technologies. Operation analysis. Testing; Digital circuits; Digital switching noise; Digital systems; Electric, optical and optoelectronic circuits; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Integrated circuit noise; Integrated circuits; Logic circuits; Logic gates; power spectral density; Semiconductor device modeling; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; shot noise; Signal processing; stochastic processes; Switching circuits; Theoretical study. Circuits analysis and design
• ISSN: 1063-8210; 1557-9999
• DOI: 10.1109/TVLSI.2009.2025883

In this paper, we present a model to derive statistical properties of digital noise due to logic transitions of gates in a fully CMOS combinational circuit. Switching activity of logic gates in a digital system is a deterministic process, depending on both circuit parameters and input signals. However, the huge number of logic blocks in a complex IC makes digital switching a cognitively stochastic process. For a combinational logic network, we can model digital switching currents as stationary shot noise processes, deriving both their amplitude distributions and their power spectral densities. From the spectra of digital currents, we can also calculate the spectral components and the rms value of disturbances injected into the on-chip power supply lines. The stochastic model for switching currents has been validated by comparing theoretical results with circuit simulations.