Electrostatic discharge protection circuit
AssigneeOki Electric Industry Co., Ltd.
InventorAtsushi NAGAYAMA
Life of this patent
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Abstract
An NMOS diode-connected in a backward direction between a power supply terminal and a ground terminal is provided as a protective element. Further, a band-pass blocking filter for blocking the passage of a frequency component of an ESD current is provided between the power supply terminal and an internal circuit. Thus, the inflow of an ESD current having a high frequency component into the internal circuit is blocked by the filter. When a potential VDD at the power supply terminal rises, the NMOS used as the protective element breaks down precedently. Thus, the voltage at the power supply terminal is reduced and hence the internal circuit is protected from the ESD current.
Claims8
An electrostatic discharge protection circuit for protecting an internal circuit from an electrostatic discharge current applied to a power supply terminal of a semiconductor integrated circuit, comprising:
- a protective element which is connected between the power supply terminal and a ground terminal and breaks down when a voltage of a constant value or larger is applied;
- and
- a filter which is provided between the power supply terminal and the internal circuit and blocks passage of a frequency component of the electrostatic discharge current.
Dependencies are inferred from the claim text.