Supply voltage independent sensing circuit for electrical fuses
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsJui-Jen Wu, Yung-Lung Lin
Life of this patent
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Abstract
A sensing circuit is disclosed for sensing a programming state of an electrical fuse, comprising. An electrical fuse is coupled to a supply voltage. A first transistor is serially coupled between the electrical fuse and a complementary supply voltage. An inverter sense amplifier is coupled to a node between the electrical fuse and the first transistor for outputting a logic signal whose value is determined based on a comparison between a resistance of the electrical fuse and a predetermined reference resistance. A bias circuit applies a bias independent of variation of the first voltage to a gate of the first transistor, such that the predetermined reference resistance is substantially insensitive to the variation of the first voltage.
Claims19
A sensing circuit for sensing a programming state of an electrical fuse, comprising:
- an electrical fuse coupled to a first voltage;
- a first transistor serially coupled between the electrical fuse and a second voltage that is lower than the first voltage;
- an inverter sense amplifier coupled to a node between the electrical fuse and the first transistor for outputting a logic signal whose value is determined based on a comparison between a resistance of the electrical fuse and a predetermined reference resistance;
- and
- a bias circuit for applying a bias independent of variation of the first voltage to a gate of the first transistor, such that the predetermined reference resistance does not change substantially due to the variation of the first voltage.
A bias circuit for generating a substantially constant bias utilized in a sense circuit that senses a programming state of an electrical fuse, comprising:
- a first PMOS transistor coupled to the supply voltage;
- a first NMOS transistor serially coupled between the first PMOS transistor and ground;
- a second PMOS transistor coupled to the supply voltage having its gate connected to its drain and to a gate of the first PMOS transistor;
- a second NMOS transistor serially coupled to the second PMOS transistor, having its gate connected to a gate and drain of the second NMOS transistor;
- and
- a resistor serially coupled between the second NMOS transistor and ground, such that the bias at a node between the first PMOS transistor and the first NMOS transistor is substantially constant, independent of variation of the supply voltage.
A sensing circuit for sensing a programming state of an electrical fuse, comprising:
- an electrical fuse coupled to a first voltage;
- a first transistor serially coupled between the electrical fuse and a second voltage that is lower than the first voltage;
- an inverter sense amplifier coupled to a node between the electrical fuse and the first transistor for outputting a logic signal whose value is determined based on a comparison between a resistance of the electrical fuse and a predetermined reference resistance;
- a first PMOS transistor coupled to the first voltage;
- a second NMOS transistor serially coupled between the first PMOS transistor and the second voltage;
- a second PMOS transistor coupled to the first voltage having its gate connected to its drain and to a gate of the first PMOS transistor;
- and
- a third NMOS transistor serially coupled to the second PMOS transistor, having its gate connected to a gate and drain of the second NMOS transistor;
- and
- a resistor serially coupled between the third NMOS transistor and the second voltage,
- wherein an output node between the first PMOS transistor and the second NMOS transistor connected to a gate of the first transistor has a substantially constant potential independent of variation of the first voltage, such that the predetermined reference resistance does not change substantially due to the variation of the first voltage.
Dependencies are inferred from the claim text.