Electrostatic discharge protection circuit

An electrostatic discharge (ESD) protection circuit comprising:

• a first rectifier unit including a first stacked diode generated by connecting a plurality of rectifier elements in a form of a stack and a first reversed diode, and configured to connect another end of the first stacked diode and another end of the first reversed diode to a common ground;
• a second rectifier unit including a second stacked diode generated by connecting a plurality of rectifier elements in a form of a stack and a second reversed diode, and configured to connect another end of the second stacked diode and another end of the second reversed diode to the common ground,
• a second stage ESD protection circuit including a fourth resistance (R4) connected to one side of a crystal oscillator, a third rectifier unit connected to the fourth resistance (R4), a sixth resistance (R6) connected to another side of the crystal oscillator, and a fourth rectifier unit connected to the sixth resistance (R6);
• and
• a first stage ESD protection circuit including a fifth resistance (R5) connected to a contact of the fourth resistance (R4) and the third rectifier unit, the first rectifier unit connected to the fifth resistance (R5), a seventh resistance (R7) connected to a contact of the sixth resistance (R6) and the fourth rectifier unit, and the second rectifier unit connected to the seventh resistance (R7),
• wherein an electrostatic shock applied to an input and output (IO) port of the first rectifier unit and the second rectifier unit flows to a discharge path according to an operation mode and the electrostatic shock is discharged to the common ground.