Electrostatic discharge protection circuit using diodes

An electrostatic discharge protection circuit positioned between a pad input terminal and a circuit device and having a supply voltage terminal and a substrate voltage terminal, the electrostatic discharge protection circuit comprising:

• first means for protecting the circuit device from a substantially positive electrostatic discharge by conducting current in a forward diode direction from the pad input terminal towards the supply voltage terminal;
• second means for protecting the circuit device from a substantially negative electrostatic discharge by conducting current in a forward diode direction from the supply voltage terminal towards the pad input terminal;
• third means for protecting the circuit device from a substantially negative electrostatic discharge by conducting current in a forward diode direction from the substrate voltage terminal towards the pad input terminal;
• and
• fourth means for protecting the circuit device from a substantially positive electrostatic discharge by conducting current in a forward diode direction from the pad input terminal towards the substrate voltage terminal.

A method for protecting a circuit device having a supply voltage and a substrate voltage from an electrostatic discharge at a pad voltage, the method comprising:

• protecting the circuit device from a substantially positive electrostatic discharge by conducting current in a forward diode direction from the pad voltage towards the supply voltage;
• protecting the circuit device from a substantially negative electrostatic discharge by conducting current in a forward diode direction from the supply voltage towards the pad voltage;
• protecting the circuit device from a substantially negative electrostatic discharge by conducting current in a forward diode direction from the substrate voltage towards the pad voltage;
• and
• protecting the circuit device from a substantially positive electrostatic discharge by conducting current in a forward diode direction from the pad voltage towards the substrate voltage.