Method and apparatus for floating or applying voltage to a well of an integrated circuit

A set of lithographic masks determining a layout of an integrated circuit design, an integrated circuit described by the masks including:

• a substrate;
• an n-well in the substrate having a range of n-well depths relative to a surface plane including a deepest n-well depth relative to the surface plane;
• a device in the n-well having at least one terminal with a range of n-well terminal depths relative to the surface plane including a deepest n-well terminal depth relative to the surface plane shallower, relative to the surface plane, than the deepest n-well depth;
• a p-well in the substrate having a range of p-well depths relative to the surface plane including a deepest p-well depth relative to the surface plane;
• a device in the p-well having at least one terminal with a range of p-well terminal depths relative to the surface plane including a deepest p-well terminal depth relative to the surface plane shallower, relative to the surface plane, than the deepest p-well depth relative to the surface plane;
• and
• biasing circuitry providing all bias voltages required by the device in the n-well and the device in the p-well for operation, wherein during operation of the device in the n-well and the device in the p-well:
• (i) the biasing circuitry applies a bias voltage arrangement to the device in the n-well and the device in the p-well, (ii) no well bias voltage is applied by the biasing circuitry to the n-well, and (iii) no well bias voltage is applied by the biasing circuitry to the p-well,
• wherein the n-well and the p-well are physically connected directly to each other along a range of shared well depths from the surface plane to an intermediate plane in the substrate deeper than the surface plane.