High voltage protection circuit for improved oxide reliability

A structure, comprising:

• an external terminal;
• a supply voltage terminal;
• a reference terminal;
• a first transistor having a current path coupled to the external terminal and having a first control terminal;
• a capacitor coupled between the external terminal and the first control terminal;
• a second transistor having a current path coupled between the current path of the first transistor and the reference terminal and having a second control terminal;
• and
• a bias circuit coupled between the supply voltage terminal and the reference terminal, the bias circuit arranged to produce a first voltage at the first control terminal and a second voltage different from the first voltage at the second control terminal, wherein the bias circuit comprises a third transistor having a first conductivity type and a fourth transistor having a second conductivity type, the fourth transistor having a current path coupled between the first control terminal and the second control terminal.