Method for DC/DC conversion and DC/DC converter arrangement including four switching phases

1. A method for DC/DC conversion, comprising the steps of:

controlling a first switch for coupling a supply terminal to a first terminal of an inductor;

controlling a second switch for coupling the first terminal of the inductor to a ground potential terminal;

controlling a third switch for coupling a second terminal of the inductor to the ground potential terminal;

controlling a fourth switch for coupling the second terminal of the inductor to an output terminal; and

performing a control sequence which comprises four switching phases, wherein

the first switch is in a closed switching position during a first, second and third switching phase and in an open switching position during a fourth switching phase,

the second switch is in a closed switching position during the fourth switching phase and in an open switching position during the first, second and third switching phase,

the third switch is in a closed switching position during the second switching phase and in an open switching position during the first, third and fourth switching phase, and

the fourth switch is in a closed switching position during the first, third and fourth switching phase and in an open switching position during the second switching phase,

wherein the first switching phase has a predetermined duration set by a first delay circuit, and the third switching phase has a further predetermined duration set by a second delay circuit.

2. The method according to claim 1 , wherein the control sequence controls the first, the second, the third and the fourth switch and a maximum of two switches out of a set comprising the first, the second, the third and the fourth switch change their switching position at a respective transition of subsequent switching phases.

3. The method according to claim 1 , wherein a maximum of one out of a subset comprising the first and the second switch is in the closed switching position in each of the switching phases and a maximum of one out of a subset comprising the third and the fourth switch is in the closed switching position in each of the switching phases.

4. The method according to claim 1 , wherein each of the first, the second, the third and the fourth switch change their switching position at least once during a complete cycle comprising each of the switching phases.

5. The method according to claim 1 , wherein the control sequence comprises:

the second switching phase having a first controllable duration,

the fourth switching phase having a second controllable duration,

the third switching phase having a first predetermined duration, and

the first switching phase having a second predetermined duration, wherein

an output voltage which is provided to the output terminal is a function of a value of the first controllable duration, of the value of the second controllable duration, of the value tp 1 of the first predetermined duration, of the value of the second predetermined duration and of a supply voltage.

6. The method according to claim 5 , wherein the value of the first controllable duration and the value of the second controllable duration are selected according to the equations:

V ref0 /Vb =( td 1 +tp 1 +tp 2)/( td 2 +tp 1 +tp 2) and T=td1 +td 2 +tp 1 +tp 2,

wherein Vref 0 is a value of a predetermined reference voltage of the output voltage, Vb is a value of the supply voltage provided at the supply terminal, tp 1 is a value of the first predetermined duration, tp 2 is a value of the second predetermined duration, and T is a predetermined cycle duration.

7. A DC/DC converter arrangement, comprising;

a first switch for coupling a supply terminal to a first terminal of an inductor;

a second switch for coupling the first terminal of the inductor to a ground potential terminal;

a third switch for coupling a second terminal of the inductor to the ground potential terminal;

a fourth switch for coupling the second terminal of the inductor to an output terminal; and

a control circuit, which is coupled to

a control input of the first switch,

a control input of the second switch,

a control input of the third switch and

a control input of the fourth switch, and

wherein said control circuit is adapted for providing a control sequence which comprises four switching phases, wherein

the first switch is in a closed switching position during a first, second and third switching phase and in an open switching position during a fourth switching phase,

the second switch is in a closed switching position during the fourth switching phase and in an open switching position during the first, second and third switching phase,

the third switch is in a closed switching position during the second switching phase and in an open switching position during the first, third and fourth switching phase, and

the fourth switch is in a closed switching position during the first, third and fourth switching phase and in an open switching position during the second switching phase,

wherein the control circuit comprises a first delay circuit and a second delay circuit, the first delay circuit sets a predetermined duration of the first switching phase, and the second delay circuit sets a further predetermined duration of the third switching phase.

8. The DC/DC converter arrangement according to claim 7 , wherein the control sequence controls the first, the second, the third and the fourth switch and a maximum of two switches out of the set comprising the first, the second, the third and the fourth switch change their switching position at a respective transition of subsequent switching phases.

9. The DC/DC converter arrangement according to claim 7 , wherein the control circuit comprises a first differential amplifier having a first input terminal which is coupled to the output terminal, having a second input terminal to which a reference voltage is applied and having an output terminal to provide a signal which controls a timing of at least one of the transitions of the subsequent switching phases.

10. The DC/DC converter arrangement according to claim 7 , wherein the DC/DC converter arrangement comprises means for measurement of an inductor current for controlling a timing of at least one of the transitions of the subsequent switching phases.

11. The DC/DC converter arrangement according to claim 10 , wherein the means for measurement of the inductor current comprises a resistor which is connected to the inductor in order to provide a current measurement.

12. The DC/DC converter arrangement according to claim 11 , wherein the means for measurement of the inductor current comprises a second differential amplifier having a first input terminal which is coupled to a first terminal of the resistor, having a second input terminal which is coupled to a second terminal of the resistor and having an output terminal to provide a signal which controls the timing of at least one of the transitions of the subsequent switching phases.

13. The DC/DC converter arrangement according to claim 7 , wherein the first delay circuit sets at least one of a first and a second predetermined duration of the respective switching phase.

14. The DC/DC converter arrangement according to claim 7 , wherein the first and the fourth switch each comprise a p-channel field-effect transistor and the second and the third switch each comprise an n-channel field-effect transistor.

15. The DC/DC converter arrangement according to claim 7 , wherein the control circuit comprises a first logic gate having an output terminal which is coupled to the control input of the first and the second switch and a second logic gate having an output terminal which is coupled to the control input of the third and the fourth switch to provide a respective control signal to each control input.