Method and apparatus for isolating circuits using deep substrate n-well

Abstract

Techniques to isolate noise-sensitive circuits from noise generated by nearby circuits. In one design, a quiet region is formed on a die when surrounded by a deep n-well formed on top of a p-type substrate. The deep n-well is heavily doped n-type and forms a depletion region at the junction with the p-type substrate. The depth and width of the depletion region is dependent on the doping concentration of the deep n-well and the amount of reverse bias voltage applied to the deep n-well. In general, a wider and deeper depletion region may be formed by more heavily doping the deep n-well and applying a higher reverse bias voltage. By properly constructing the deep n-well and applying a high reverse bias voltage, a deep and wide depletion region may be formed to provide a barrier against noise from entering the quiet region.

Dependencies are inferred from the claim text.