Electrical fuse for integrated circuits

An electrically programmable fuse comprising:

• a first metal-oxide-semiconductor (MOS) transistor, the first MOS transistor having a nominal snapback voltage, wherein the first MOS transistor comprises a first p-type MOS (PMOS) transistor;
• an n-type MOS (NMOS) transistor, the NMOS transistor being coupled between a drain of the first MOS transistor and ground;
• and
• a regulating element coupled between a gate of the first MOS transistor and a source of the first MOS transistor for lowering a snapback voltage of the first MOS transistor below the nominal snapback voltage, wherein the regulating element is a resistive element comprising a second PMOS transistor, wherein a drain of the second PMOS transistor is connected to the gate of the first MOS transistor, and wherein a source of the second PMOS transistor and a gate of the second PMOS transistor are connected to the source of the first MOS transistor.

An integrated circuit (IC) comprising:

• a first metal-oxide-semiconductor (MOS) transistor designed for a nominal operating voltage, the first MOS transistor having a nominal snapback voltage, wherein the first MOS transistor comprises a first n-type MOS (NMOS) transistor, wherein the source of the first MOS transistor is connected to ground;
• a regulating element coupled between a gate of the first MOS transistor and a source of the first MOS transistor for lowering a snapback voltage of the first MOS transistor below the nominal snapback voltage, wherein the regulating element is a resistive element comprising a second NMOS transistor, wherein a drain of the second NMOS transistor is connected to the gate of the first MOS transistor, and wherein a source of the second NMOS transistor and a gate of the second NMOS transistor are connected to ground;
• and
• a control circuit for selectively providing the nominal operating voltage and a programming voltage to the first MOS transistor, the programming voltage being greater than the nominal operating voltage, wherein the control circuit is connected to a drain of the first MOS transistor.

A method for programming a first metal-oxide-semiconductor (MOS) transistor in an integrated circuit (IC), the method comprising:

• providing a regulating element coupled between a gate of the first MOS transistor and a source of the first MOS transistor, wherein the first MOS transistor comprises a first n-type MOS (NMOS) transistor, and wherein the regulating element comprises a second NMOS transistor, a drain of the second NMOS transistor being connected to the gate of the first MOS transistor, and a source of the second NMOS transistor and a gate of the second NMOS transistor being connected to ground;
• applying a programming voltage across the first MOS transistor to place the first MOS transistor in snapback mode;
• and
• operating the first MOS transistor in snapback mode until thermal breakdown of the first MOS transistor occurs.

An electrically programmable fuse comprising:

• a first metal-oxide-semiconductor (MOS) transistor having a source terminal coupled to a voltage supply;
• and
• a regulating element coupled between a gate terminal of the first MOS transistor and the source terminal of the first MOS transistor:
• wherein the first MOS transistor is permanently shorted such that current flows between the source terminal of the first MOS transistor and a drain terminal of the first MOS transistor regardless of a gate voltage applied at the gate terminal of the first MOS transistor;
• wherein the regulating element comprises a second MOS transistor having a gate terminal, a source terminal, and a drain terminal;
• wherein the drain terminal of the second MOS transistor is coupled to the gate terminal of the first MOS transistor;
• and
• wherein the source terminal of the second MOS transistor and the gate terminal of the second MOS transistor are coupled to the voltage supply.