Modeling of substrate noise coupling for nMOS transistors in heavily doped substrates

An n-contact to p-contact model is proposed for analyzing substrate noise coupling in mixed-signal integrated circuits. The model takes advantage of an existing p-contact to p-contact model and combines it with a new concept of virtual separation. The virtual separation concept has been validated with three-dimensional device simulations and measurements from test structures fabricated in a 0.35 /spl mu/m CMOS heavily doped process. This model is useful when transistor switching noise is the dominant source of substrate noise coupling.