Electronic switch for decoupling capacitor

A self-isolating decoupling capacitor for use in an integrated circuit comprising:

• a semiconductor substrate;
• an n-well in a surface of the substrate, said n-well having a plurality of edges extending to the surface of the substrate and said n-well having a depth substantially greater than diffused regions of active devices formed in said substrate;
• a capacitor having a first electrode comprising a conductive layer dielectrically spaced from the surface of said n-well, said n-well comprising the second electrode of said capacitor;
• a control device for connecting the n-well to a reference potential;
• said control device extending along at least one edge of said n-well;
• a first conductor coupled between said first electrode and a voltage node to be provided decoupling capacitance protection;
• and
• a second conductor coupled between the control device and a control signal.