Level-shifter circuit

1. A level-shift circuit, comprising:

an input, for receiving a first voltage;

an output, for outputting a second voltage;

a resistor array comprising a plurality of resistors connected in series to the input;

a current sink for providing a current that is independent of the first voltage;

a first switch arrangement comprising a first plurality of switches connected between terminals of the resistor array and an input of the current sink, for establishing a selected one from a plurality of force paths between the current sink and the input, said selected force path comprising a selected number of said plurality of resistors of said resistor array; and

a second switch arrangement comprising a second plurality of switches connected between the output and terminals of the resistor array that provides a sense path between the resistor array and the output that does not comprise any of said first plurality of switches used to establish each of said plurality of force paths.

2. A level-shift circuit as claimed in claim 1 , wherein the first switch arrangement comprises:

a first switch connection on a high side of said plurality of resistors of said resistor array; and

a second switch connection on a low side of said plurality of resistors of said resistor array.

3. A level-shift circuit as claimed in claim 1 , said first switch arrangement comprising:

at least one intermediate switch connection to a common node of a pair of adjacent resistors of said plurality of resistors.

4. A level-shift circuit as claimed in claim 3 , wherein said first switch arrangement comprises a plurality of respective intermediate switch connections to common nodes of pairs of respective adjacent resistors of said plurality of resistors.

5. A level-shift circuit as claimed in claim 2 , wherein said first switch arrangement comprises a switch connected between two terminals of said plurality of resistors.

6. A level-shift circuit as claimed in claim 1 , wherein the second plurality of switches is for establishing a selected one from a plurality of sense paths between the resistor array and the output.

7. A level-shift circuit as claimed in claim 6 , wherein the second switch arrangement comprises:

a third switch connection on a high side of said plurality of resistors of said resistor array; and

a fourth switch connection on a low side of said plurality of resistors of said resistor array.

8. A level-shift circuit as claimed in claim 6 , said second switch arrangement comprising:

at least one second intermediate switch connection to a common node of a pair of adjacent resistors of said plurality of resistors.

9. A level-shift circuit as claimed in claim 8 , wherein said second switch arrangement comprises a plurality of second respective intermediate switch connections to common nodes of pairs of respective adjacent resistors of said plurality of resistors.

10. A level-shift circuit as claimed in claim 6 wherein the first and second switch arrangements are controllable such that a single switch of the first plurality of switches and a single switch of the second plurality of switches are closed at any one time.

11. A level-shift circuit as claimed in claim 10 , wherein said single switch of the first plurality of switches and said single switch of the second plurality of switches are connected to the same resistor terminal.

12. A level-shift circuit as claimed in claim 6 , wherein the sense path comprises a resistor of the resistor array.

13. A level-shift circuit as claimed in claim 12 , wherein the force path comprises a resistor of the resistor array coupled between the sense path and the current sink.

14. A level-shift circuit as claimed in claim 1 , wherein each resistor of said plurality of resistors has the same value of resistance.

15. A level-shift circuit as claimed in claim 1 , wherein, in use, the output is coupled to a relatively high impedance component, such that a relative majority of current flows through the force path and a relative minority of current flows through the sense path.

16. A level-shift circuit as claimed in claim 1 , wherein the current sink comprises a second resistor, and the value of the current generated by the current sink is inversely proportional to the resistance of the second resistor.

17. A level-shift circuit as claimed in claim 16 , wherein the current sink has an input for receiving a reference voltage and wherein the value of the current generated by the current sink is proportional to said reference voltage.

18. A level-shift circuit as claimed in claim 16 , wherein the second resistor is manufactured using the same material as the plurality of resistors in said resistor array.

19. A level-shift circuit as claimed in claim 18 , wherein the second resistor is manufactured using unit elements of the same type as unit elements used to manufacture the plurality of resistors in said resistor array.

20. A level-shift circuit as claimed in claim 16 , wherein the second resistor is physically located adjacent to, or interleaved with, the plurality of resistors of said resistor array.

21. A level-shift circuit as claimed in claim 1 , wherein the current sink comprises a MOS transistor and said current is the drain current of the MOS transistor.

22. A circuit, comprising:

a circuit input, for receiving a reference voltage;

a circuit output, for outputting an output voltage;

a feedback path coupled to said circuit output, comprising a level-shift circuit as claimed in claim 1 ; and

control circuitry, for comparing said reference voltage and said second voltage, and controlling said output voltage in dependence on said comparison.

23. A circuit as claimed in claim 22 , wherein said control circuitry comprises a comparator or amplifier.

24. A circuit as claimed in claim 22 , wherein the output voltage is said first voltage.

25. A circuit as claimed in claim 22 , wherein the circuit is a power regulator circuit.

26. An integrated circuit comprising a level-shift circuit as claimed in claim 1 .

27. An electronic device comprising a level-shift circuit as claimed in claim 1 .

28. An electronic device as claimed in claim 27 wherein the device is one of: a portable computing device; a laptop computer; a personal data assistant; a personal media player; an mp3 player; a portable television; a mobile communications device; a mobile telephone; a navigation aid; a GPS device; a game console.

29. A level-shift circuit, comprising:

an input, for receiving a first voltage;

an output, for outputting a second voltage;

a resistor array comprising a plurality of resistors connected in series to the input;

a current sink for providing a current that is independent of the first voltage;

a first switch arrangement connected between an input of the current sink and terminals of the resistor array, the first switch arrangement comprising a first plurality of switches for establishing a selected one from a plurality of force paths between the current sink and the input, said selected force path comprising a selected number of said plurality of resistors of said resistor array; and

a second switch arrangement comprising a second plurality of switches connected between the output and terminals of the resistor array, said second switch arrangement providing a sense path between a node of the resistor array and the output, said sense path meeting but not comprising any of said selected force path.

30. A level-shift circuit, comprising:

an input, for receiving a first voltage;

an output, for outputting a second voltage;

a resistor array comprising a plurality of resistors connected in series to the input;

a current sink for providing a current that is independent of the first voltage;

a first switch arrangement connected between an input of the current sink and terminals of the resistor array, the first switch arrangement comprising a first plurality of switches for establishing a selected one from a plurality of force paths between the current sink and the input, said selected force path comprising a selected number of said plurality of resistors of said resistor array; and

a second switch arrangement comprising a second plurality of switches coupled between the output and terminals of the resistor array, said second switch arrangement providing part or all of a sense path between a node of the resistor array and the output, said sense path meeting the force path at said node but not comprising any resistors or switches of said selected force path.

31. A method of providing a level-shifted voltage from a first voltage, the method comprising:

receiving the first voltage at an input;

establishing a selected one from a plurality of force paths between a current sink and the input by controlling a first plurality of switches connected between terminals of a resistor array and an input of the current sink, said selected force path comprising a selected number of a plurality of resistors of the resistor array, said resistor array being coupled in series to the input, said current sink providing a current that is independent of the first voltage;

establishing a sense path by controlling a second plurality of switches connected between terminals of the resistor array and an output that does not comprise any switches of the first plurality of switches used to establish each of said plurality of force paths; and

outputting said level shifted voltage at said output.

32. A method of operating a circuit, comprising:

receiving a reference voltage and a feedback voltage;

comparing said reference voltage and said feedback voltage,

generating a circuit output voltage in dependence on said comparison; and

providing said feedback voltage, level-shifted from said circuit output voltage according to the method of claim 31 .