Apparatus for Rectified RC Trigger of Back-to-Back MOS-SCR ESD Protection

An apparatus, comprising:

• an external terminal for coupling to a signal;
• a first SCR device having a first source terminal coupled to the external terminal, having a first gate terminal coupled through a first gate resistor to the external terminal, and having a first drain terminal, and having a first body terminal tied to the first source terminal;
• a second SCR device having a second drain terminal coupled to the first drain terminal, a second gate terminal coupled to an external reference voltage terminal through a second gate resistor, a second source terminal coupled to the external reference voltage terminal, and a second body terminal coupled to the second source terminal;
• a third SCR device having a third source terminal coupled to the external terminal, a third gate terminal coupled to the first gate terminal of the first SCR device, a third body terminal coupled to the third source terminal, and having a third drain terminal;
• a first capacitor coupled between the third drain terminal and the second gate terminal of the second SCR device;
• and
• a second capacitor coupled between the second gate terminal and the external reference voltage terminal.