Applied Mathematics & Information Sciences

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In this paper the effects of substrate coupling on analog circuits in a mixed-signal chip are described and analyzed based on simulated results. Substrate coupling is a major challenge for mixed-signal design. To analyse the substrate coupling with digital circuits and analog circuit simulation accurate substrate model is important in the modern mixed-signal IC design. At the higher operating frequency the capacitive effect in substrate becomes important and the substrate impedances become frequency dependent in lightly doped substrate. To balance this, heavily doped substrate is used for the analysis and assumed as resistive network. The noise coupling is demonstrated by simulation on 0.18 mm heavily doped CMOS process.