Electrostatic protection circuit
AssigneeNEC Corporation
InventorYasutaka Uenishi
Life of this patent
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Abstract
An electrostatic protection circuit protects an internal circuit from electric charge which is applied via an electrode pad. The above electrostatic protection circuit mainly includes a protection transistor portion, a second transistor and a third transistor. In this case, the protection transistor portion includes a first transistor having a first gate electrode in order to protect the internal circuit by discharging the electric charge. The second transistor controls so as to keep the first gate electrode into a floating state before the power source is introduced. The third transistor gives a predetermined potential into the first gate electrode.
Claims3
An electrostatic protection circuit which protects an internal circuit from electric charge which is applied via an electrode pad and which is coupled to a power source, comprising:
- a protection transistor portion which includes at least one first transistor having a first gate electrode in order to protect said internal circuit by discharging the electric charge via said first transistor;
- a first protection control transistor portion which includes at least one second transistor which controls so as to keep the first gate electrode into a floating state before the power source is introduced;
- and
- a second protection control transistor portion which includes at least one third transistor which gives a predetermined potential to the first gate electrode
- wherein said protection transistor portion includes a plurality of said first transistors each of which has a breakdown voltage, and
- said third transistor is arranged closer to said first transistor than said second transistor so as to uniformly reduce the breakdown voltages, and
- wherein an amplification factor of said second transistor is optimized with an amplification factor of another second transistor in said first protection control transistor portion, and wherein said amplification factor of said second transistor is smaller than that of said third transistor.
An electrostatic protection circuit which protects an internal circuit from electric charge which is applied via an electrode pad and which is coupled to a power source, comprising:
- a protection transistor portion which includes at least one first transistor having a first gate electrode in order to protect said internal circuit by discharging the electric charge via said first transistor;
- a second transistor which controls so as to keep the first gate electrode into a floating state before the power source is introduced;
- and
- a third transistor which gives a predetermined potential to the first gate electrode wherein said first transistor further includes first source and drain electrodes, said second transistor includes second source, drain and gate electrodes, said third transistor includes third source, drain and gate electrodes,
- said first gate electrode being connected to said second drain electrode and said second drain electrode being connected to said third drain electrode,
- said third transistor is arranged close to said first transistor to improve an amplification factor of said third transistor on the condition that a gate width of said third gate electrode is made wider.
An electrostatic protection circuit which protects an internal circuit from electric charge which is applied via an electrode pad and which is coupled to a power source, comprising:
- a protection transistor portion which includes at least one first transistor having a first gate electrode in order to protect said internal circuit by discharging the electric charge via said first transistor;
- a second transistor which controls so as to keep the first gate electrode into a floating state before the power source is introduced;
- and
- a third transistor which gives a predetermined potential to the first gate electrode
- wherein said first transistor further includes first source and drain electrodes,
- said second transistor includes second source, drain and gate electrodes,
- said third transistor includes third source, drain and gate electrodes,
- said first gate electrode being connected to said second drain electrode and said second drain electrode being connected to said third drain electrode,
- said third transistor is arranged farther from said first transistor than said second transistor.
Dependencies are inferred from the claim text.