Power converter and method for power conversion

1. A power converter configured to receive a first electrical power signal and to generate a second electrical power signal, the second electrical power signal having a voltage with a DC component, the power converter comprising:

a first output terminal and a second output terminal configured to deliver the voltage; and

a control circuit configured to measure the voltage and to control operation of the power converter in accordance with a measurement voltage, the control circuit including

a voltage level shifter configured to generate the measurement voltage by subtracting from the voltage a difference between a reference voltage and a desired output voltage to adjust the DC component of the voltage, and

a comparator, wherein the voltage level shifter has a first terminal coupled to the first output terminal, a second terminal coupled to the second output terminal and a third terminal coupled to an input of the comparator.

2. A power converter as claimed in claim 1 , wherein the voltage level shifter comprises:

a resistor coupled between the first output terminal and an intermediate node; and

a current source coupled between the intermediate node and the second output terminal, the current source configured to generate a reference current through the resistor,

wherein the voltage level shifter is configured to generate the measurement voltage signal between the intermediate node and the second output terminal.

3. A power converter as claimed in claim 2 , wherein the resistor comprises an adjustable resistance circuit configured to adjust a resistance of the resistor.

4. A power converter as claimed in claim 3 , wherein the resistor comprises a plurality of resistive elements connected in series and the adjustable resistance circuit comprises short-circuit switches configured to selectively short-circuit resistive elements out of said plurality of resistive elements.

5. A power converter as claimed in claim 3 , wherein the resistor comprises a plurality of resistive elements connected in parallel between the first output terminal and the intermediate node and the adjustable resistance circuit comprises disconnection switches configured to selectively disconnect resistive elements out of said plurality of resistive elements.

6. A power converter as claimed in claim 2 , wherein the current source is configured to adjust the reference current.

7. A power converter as claimed in claim 6 , wherein the current source comprises:

a transistor having a control electrode and a main conductive path;

an amplifier having a first input, a second input, and an output; and

a current adjustment resistor having a first electrode and a second electrode, wherein:

the first electrode of the current adjustment resistor is coupled to the intermediate node via the main conductive path of the transistor;

the second electrode of the current adjustment resistor is coupled to the second output terminal;

the output of the amplifier is coupled to the control electrode of the transistor;

the first input of the amplifier is arranged for receiving a current adjustment voltage; and

the second input of the amplifier is coupled to the first electrode of the current adjustment resistor.

8. An integrated circuit comprising a power converter as claimed in claim 1 .

9. An apparatus comprising:

a power converter as claimed in claim 1 ; and

a battery configured to supply the first electrical power signal.

10. A method for converting a first electrical power signal into a second electrical power signal, the second electrical power signal comprising a voltage having a DC component, the method comprising

generating a measurement voltage by adjusting the DC component of the voltage using a level shifter coupled to the voltage and producing the adjusted DC component of the voltage; and

controlling operation of a power converter in accordance with the measurement voltage by comparing the adjusted DC component of the voltage from the level shifter with a reference voltage, wherein the power converter converts the a first electrical power signal into the second electrical power signal,

wherein adjusting the DC component of the voltage comprises subtracting from the voltage a difference between a first reference voltage and a desired voltage.

11. The method of claim 10 , wherein the power converter generates the output voltage between a first output terminal and a second output terminal, wherein generating a measurement voltage comprises

generating the measurement voltage between an intermediate node and the second output terminal by generating a reference current through a resistor coupled between the first output terminal and the intermediate node.

12. The method of claim 11 , wherein generating a measurement voltage further comprises adjusting a resistance of the resistor.

13. The method of claim 12 , wherein the resistor comprises a plurality of resistive elements connected in series, and wherein adjusting a resistance of the resistor comprises short-circuiting selected ones of the plurality of resistive elements.

14. The method of claim 12 , wherein the resistor comprises a plurality of resistive elements connected in parallel between the first output terminal and the intermediate node, and wherein adjusting a resistance of the resistor comprises disconnecting selected ones of the plurality of resistive elements.

15. The method of claim 11 , further comprising adjusting the reference current.

16. The method of claim 15 , wherein:

the reference current is generated between the intermediate node and the second output terminal;

a main conductive path of a transistor and a current adjustment resistor are coupled in series between the intermediate node and the second output terminal; and

generating the reference current comprises controlling the transistor according to a comparison between a second reference voltage and a voltage across the current adjustment resistor.

17. The method of claim 16 , wherein adjusting the DC component of the voltage comprises subtracting from the voltage a difference between a first reference voltage and a desired voltage, the method further comprising generating the second reference voltage from the first reference voltage.

18. The method of claim 10 , further comprising supplying the first electrical power signal from a battery.

19. A power converter as claimed in claim 1 , wherein

the control circuit further comprises a second comparator, the third terminal of the voltage level shifter coupled to an input of the second comparator, and

the control circuit is configured to control the operation of the power converter to maintain the voltage in a range of voltages derived from a first reference voltage coupled to the first comparator and a second reference voltage coupled to the second comparator.

20. The method of claim 10 , wherein operation of the power converter is controlled to maintain the voltage in a range of voltages derived from the reference voltage and a second reference voltage.