Transistor protection circuit
AssigneeOki Electric Industry Co., Ltd.
InventorsShinnichi Fukuzako, Yasuhiro Fukuda
Life of this patent
Estimating the term…
Abstract
The transistor protection device provides a circuit capable of obtaining a sufficient discharge characteristic when an electrostatic discharge voltage is applied to a semiconductor integrated circuit composed of a bipolar transistor. The protection device is provided across an emitter-base (E-B) junction of the bipolar transistor. When an electrostatic discharge voltage for biasing the E-B junction in the reverse direction is applied, the protection device is turned on and the surge current flows through the protection device such that the current which flows into the E-B junction of the transistor is greatly reduced so as to prevent electrostatic breakdown.
Claims32
A transistor protection circuit for protecting a bipolar transistor including at least one terminal, said bipolar transistor biasing an emitter-base junction thereof in the reverse direction when an electrostatic discharge is externally applied to said at least one terminal, comprising:
- a protection device operatively directly coupled across the emitter-base junction so that the protection device protects the emitter-base junction against a negative electrostatic discharge, and the emitter-base junction protects the protection device against a positive electrostatic discharge.
A transistor protection circuit for protecting a bipolar transistor having at least one terminal, an emitter and a base, said bipolar transistor biasing an emitter-base junction thereof in the reverse direction when an electrostatic discharge is externally applied to said at least one terminal, comprising:
- a protection device operatively coupled to the at least one terminal and operatively directly coupled to the emitter of the bipolar transistor;
- and
- a first resistor operatively coupled between the base of the bipolar transistor and said protection device;
- wherein said protection device protects the emitter-base junction against a negative electrostatic discharge, and the emitter-base junction protects said protection device against a positive electrostatic discharge.
A transistor protection circuit for protecting a bipolar transistor having a base, connected to an input terminal, and an emitter, said bipolar transistor biasing an emitter-base junction thereof in the reverse direction when an electrostatic discharge is applied to the input terminal, comprising:
- a protection device disposed and operatively directly coupled to both the base and the emitter of the bipolar transistor so that said protection device protects the emitter-base junction against a negative electrostatic discharge, and the emitter-base junction protects said protection device against a positive electrostatic discharge.
A transistor protection circuit for protecting a bipolar transistor having a base, connected to an input terminal, and an emitter, said bipolar transistor biasing an emitter-base junction thereof in the reverse direction when an electrostatic discharge is applied to the input terminal, comprising:
- a protection device operatively coupled to the input terminal and operatively directly coupled to the emitter of the bipolar transistor;
- and
- a first resistor disposed and operatively coupled between the base of the bipolar transistor and said protection device;
- wherein said protection device protects the emitter-base junction against a negative electrostatic discharge, and the emitter-base junction protects said protection device against a positive electrostatic discharge.
A transistor protection circuit for protecting a bipolar transistor having at least one terminal, an emitter and a base, the bipolar transistor biasing an emitter-base junction thereof in a reverse direction when an electrostatic discharge is externally applied to the at least one terminal, comprising:
- a protection device operatively coupled to the at least one terminal and operatively directly coupled across the emitter-base junction of the bipolar transistor;
- and
- a diode operatively coupled between the at least one terminal and a ground potential.
Dependencies are inferred from the claim text.