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In an embodiment, a circuit includes a first transistor having a first current electrode, a control electrode, and a second current electrode coupled to a power supply terminal. The circuit further includes a resistive element having a first terminal coupled to the control electrode of the first tra

In an embodiment, a circuit includes a first transistor having a first current electrode, a control electrode, and a second current electrode coupled to a power supply terminal. The circuit further includes a resistive element having a first terminal coupled to the control electrode of the first transistor and a second terminal coupled to the power supply terminal. The circuit also includes a feedback circuit for providing a first current to the first control electrode of the first transistor and for preserving substantially the first current related to a voltage at the control electrode of the first transistor, through the resistive element. The feedback circuit includes an output terminal for providing an output signal in response to a voltage at the control electrode of the first transistor. In an embodiment, the first transistor is a floating-gate device with programmable threshold voltage.

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1. A circuit comprising: a floating-gate transistor including a first current electrode, a control electrode, and a second current electrode coupled to a power supply terminal;a resistive element including a first terminal coupled to the control electrode of the floating-gate transistor, and a secon

1. A circuit comprising: a floating-gate transistor including a first current electrode, a control electrode, and a second current electrode coupled to a power supply terminal;a resistive element including a first terminal coupled to the control electrode of the floating-gate transistor, and a second terminal coupled to the power supply terminal; anda feedback circuit for providing a first current to the first current electrode of the floating-gate transistor, and substantially the first current to the first terminal of the resistive element, the feedback circuit having an output terminal for providing an output signal in response to a voltage at the control electrode of the floating-gate transistor. 2. The circuit of claim 1, wherein the feedback circuit comprises: a current mirror having a first terminal coupled to the first terminal of the resistive element, and a second terminal coupled to the first current electrode of the floating-gate transistor; anda second transistor including a first current electrode coupled to the first terminal of the current mirror, a control electrode coupled to the second terminal of the current mirror, and a second current electrode coupled to the first terminal of the resistive element. 3. The circuit of claim 2, wherein the feedback circuit further comprises: a third transistor including a first current electrode coupled to the second terminal of the current mirror, a control electrode coupled to the second terminal of the current mirror, and a second current electrode coupled to the first current electrode of the floating-gate transistor. 4. The circuit of claim 1, wherein the feedback circuit comprises: a current mirror having a first terminal coupled to the first terminal of the resistive Element, and a second terminal coupled to the first current electrode of the floating-gate transistor;a second transistor including a first current electrode, a control electrode coupled to the second terminal of the current mirror, and a second current electrode;a third transistor including a first current electrode coupled to the second current electrode of the second transistor, a control electrode coupled to the first terminal of the resistive element, and a second current electrode;a second resistive element including a first terminal coupled to the second current electrode of the third transistor and a second terminal coupled to the power supply terminal; anda second current mirror having a first terminal coupled to the first current electrode of the second transistor, and a second current electrode for providing an output reference current. 5. The circuit of claim 4, wherein the third transistor comprises a floating-gate transistor. 6. The circuit of claim 4, further comprising: a third resistive element having a first terminal coupled to the second terminal of the second current mirror, and a second terminal coupled to the power supply voltage terminal,whereby the first terminal of the third resistor provides an output voltage. 7. The circuit of claim 1, wherein the resistive element comprises a floating-gate transistor. 8. The circuit of claim 1, wherein the resistive element comprises a configurable switched impedance. 9. A method of producing a reference current, the method comprising: applying a voltage on a first terminal of a resistive element to generate a first current, the first terminal coupled to the control terminal of a floating-gate transistor, the resistive element including a second terminal coupled to a power supply terminal;providing substantially the first current to a first current electrode of the floating-gate transistor, the floating-gate transistor including the control terminal and a second terminal coupled to the power supply terminal; andcontrolling the first current through a feedback loop that provides an output signal in response to a voltage variation at the control terminal of the floating-gate transistor. 10. The method of claim 9, further comprising: generating a reference current related to the output signal. 11. The method of claim 10, wherein generating the reference current comprises: mirroring the output current using a current mirror coupled to the feedback loop to generate the reference current. 12. The method of claim 9, wherein before providing the first current, the method further comprises: programming a threshold voltage of the floating-gate transistor using a programming circuit. 13. The method of claim 12, wherein programming the threshold voltage comprises: comparing substantially the reference current to a test current using a comparator to produce a control signal; andselectively activating a switch to couple the programming circuit to the floating-gate transistor to program the threshold voltage. 14. The method of claim 12, wherein the feedback loop includes a second transistor comprising a floating-gate transistor, and wherein, before providing the first current, the method further comprises: programming a threshold voltage of the second transistor using a programming circuit. 15. The method of claim 14, wherein the resistive element comprises a floating-gate transistor, and wherein, before providing the first current, the method further comprises: programming a threshold voltage of the resistive element using a programming circuit. 16. A circuit comprising: a floating-gate transistor including a first current electrode, a control electrode, and a second current electrode coupled to a power supply terminal;a first resistive element including a first terminal coupled to the control electrode of the floating-gate transistor, and a second terminal coupled to the power supply terminal; anda feedback circuit for providing a first current to the first current electrode of the first transistor, and for providing substantially the first current related to a voltage at the control electrode of the floating-gate transistor, through the resistive element. 17. The circuit of claim 16, wherein the floating-gate transistor has a programmable threshold voltage. 18. The circuit of claim 16, wherein the first resistive element comprises a floating-gate transistor having a programmable threshold voltage. 19. The circuit of claim 18, further comprising a programming circuit configured to program the programmable threshold voltage of the first resistive element. 20. The circuit of claim 16, further comprising: a second transistor including a first current electrode, a control electrode coupled to the first terminal of the first resistive element, and a second current electrode; anda second resistor having a first terminal coupled to the second current electrode of the second transistor and having a second terminal coupled to the power supply terminal. 21. The circuit of claim 20, further comprising: a current mirror having a first terminal coupled to the first current electrode of the second transistor and having a second terminal configured to carry a reference current related to the output signal. 22. The circuit of claim 20, wherein the second transistor comprises a second floating-gate transistor, and wherein the circuit includes programming circuitry comprising: a plurality of switches;a first tunnel circuit including a first terminal coupled to the floating-gate transistor and at least one second terminal;a second tunnel circuit including a first terminal coupled to the second transistor and at least one second terminal;a high voltage circuit configured to receive a control signal related to a difference between a test current and a current related to the output signal, the high voltage circuit configured to selectively control each of the plurality of switches, the first tunnel circuit, and the second tunnel circuit to selectively program at least one of the floating-gate transistor and the second transistor based on the difference.