Interference suppression for switched mode power supply

1. A switched mode power supply comprising:

a first switch;

a first inductor connected with the first switch, wherein the first switch is arranged to:

connect a first terminal of the first inductor with a first voltage when the first switch is in a first switching state; and

connect the first terminal of the first inductor with a second voltage when the first switch is in a second switching state;

a first capacitor connected in parallel with the first inductor between the first terminal and a second terminal of the first inductor;

a second switch;

a second inductor connected with the second switch, wherein the second switch is arranged to:

connect a first terminal of the second inductor with the first voltage when the second switch is in a third switching state; and

connect the first terminal of the second inductor with the second voltage when the second switch is in a fourth switching state, wherein the second terminal of the first inductor and a second terminal of the second inductor are configured to provide a supply output; and

a second capacitor connected in parallel with the second inductor between the first and second terminals of the second inductor.

2. The switched mode power supply of claim 1 , wherein capacitance values of the first and second capacitors are selected based on a desired frequency of suppression at the supply output.

3. The switched mode power supply of claim 1 , further comprising a first damping resistor and a second damping resistor, wherein:

a first series connection is formed by the first damping resistor connected in series with the first capacitor, wherein the first series connection is connected in parallel between the first and second terminal of the first inductor; and

a second series connection is formed by the second damping resistor connected in series with the second capacitor, wherein the second series connection is connected in parallel between the first and second terminals of the second inductor.

4. The switched mode power supply of claim 1 , wherein the first and second capacitors each have the same capacitance value.

5. The switched mode power supply of claim 1 , further comprising:

a third capacitor, wherein the first and third capacitors are selectively connected in parallel with the first inductors;

a third switch connected in series with the third capacitor;

a fourth switch connected in series with the first capacitor;

a fourth capacitor, wherein the second and fourth capacitors are selectively connected in parallel with the second inductor;

a fifth switch connected in series with the fourth capacitor; and

a sixth switch connected in series with the second capacitor.

6. The switched mode power supply of claim 5 , further comprising a first damping resistor, a second damping resistor, a third damping resistor, and a fourth damping resistor,

wherein the damping resistance of the first damping resistor is incorporated within the fourth switch;

wherein the damping resistance of the third damping resistor is incorporated within the third switch,

wherein the damping resistance of the fourth damping resistor is incorporated within the fifth switch, and

wherein the damping resistance of the second damping resistor is incorporated within the sixth switch.

7. The switched mode power supply of claim 1 , wherein the first capacitor further comprises a bank of parallel capacitors connected in parallel between the first and second terminals of the first inductor, and the second capacitor further comprising another bank of parallel capacitors connected in parallel between the first and second terminals of the second inductor.

8. The switched mode power supply of claim 7 , wherein the bank of parallel capacitors and the other bank of parallel capacitors have capacitance values that are binary weighted.

9. The switched mode power supply of claim 8 , wherein the first capacitor is selected from the bank of capacitors such that either no capacitors, one capacitor, or more than one capacitor is selected at any time, and wherein the second capacitor is selected from the other bank of capacitors such that either no capacitors, one capacitor, or more than one capacitor is selected at any time.

10. The switched mode power supply of claim 7 , wherein each bank of capacitors has a set of capacitors of different values, each bank having a set of corresponding values.

11. The switched mode power supply of claim 7 , further comprising a bank of parallel switches for each bank of capacitors, for selectively connecting the bank of capacitors.

12. The switched mode power supply of claim 7 , further comprising a single bank of parallel switches for all banks of capacitors, for selectively connecting the capacitors.

13. The switched mode power supply of claim 7 , further comprising a damping resistor in series with each capacitor.

14. The switched mode power supply of claim 7 , wherein a resistance value of each switch is configured to dampen the supply output above a suppression frequency.

15. The switched mode power supply of claim 1 , wherein the first switch is arranged to selectively connect the first inductor to the first voltage and the second voltage, and wherein the second switch is arranged to selectively connect the second inductor to the first voltage and the second voltage in order to generate a signal level at the supply output that corresponds to an input reference signal.

16. The switched mode power supply according to claim 15 , further comprising an error amplifier for comparing the signal level at the supply output with the input reference signal and removing any error therebetween.

17. An envelope tracked power supply including a switched mode power supply according to claim 1 .

18. An RF amplification stage including a switched mode power supply according to claim 1 .