Method and apparatus for controller optimization of a switching voltage regulator

1. A method of determining control loop coefficients of a digital voltage regulator controller, the method comprising:

determining PID (proportional-integral-derivative) coefficients that meet gain and phase margin targets of a digital voltage regulator controller, as a function of a plurality of system parameters of the digital voltage regulator controller; and

optimizing one or more of the PID coefficients based on an output impedance closed loop response of the digital voltage regulator controller, wherein the one or more of the PID coefficients are optimized when a peak of the output impedance over frequency is minimized for frequencies below a bandwidth of the digital voltage regulator controller.

2. The method of claim 1 , further comprising:

permitting manual adjustment of the PID coefficients after optimizing one or more of the PID coefficients to flatten the output impedance response for frequencies below the bandwidth of the digital voltage regulator controller.

3. The method of claim 2 , further comprising:

providing a visual display of at least one of an open-loop gain response of the digital voltage regulator controller over frequency, a closed-loop gain response of the digital voltage regulator controller over frequency, and the output impedance response of the digital voltage regulator controller over frequency to aid in the manual adjustment of the one or more PID coefficients.

4. The method of claim 1 , wherein optimizing one or more of the PID coefficients comprises optimizing a proportional gain and a derivative gain of the digital voltage regulator controller to flatten the output impedance closed loop response for frequencies below the bandwidth of the digital voltage regulator controller.

5. The method of claim 1 , wherein the PID coefficients are determined as a function of a switching frequency implemented by the digital voltage regulator controller in switching one or more power stages for driving a load, a number of active power stages controlled by the digital voltage regulator controller and a maximum number of power stages for which the digital voltage regulator controller is programmed to control.

6. The method of claim 1 , further comprising:

determining a post-filter coefficient and the PID coefficients so that the gain and phase margin targets are satisfied, as a function of the system parameters; and

optimizing the post-filter coefficient and one or more of the PID coefficients based on the output impedance closed loop response of the digital voltage regulator controller, wherein the post-filter coefficient and the one or more of the PID coefficients are optimized when the peak of the output impedance over frequency is minimized for frequencies below the bandwidth of the digital voltage regulator controller.

7. The method of claim I, further comprising:

determining an adaptive voltage position (AVP) filter coefficient that meets a maximum output impedance target of the digital voltage regulator controller; and

optimizing the AVP filter coefficient and one or more of the PID coefficients based on the output impedance closed loop response of the digital voltage regulator controller, wherein the AVP filter coefficient and the one or more of the PID coefficients are optimized when the peak of the output impedance over frequency is minimized for frequencies below the bandwidth of the digital voltage regulator controller.

8. The method of claim 1 , further comprising:

determining a proportional gain and an integral gain for a current balance filter of the digital voltage regulator controller so that a bandwidth of the current balance filter is a fraction of the bandwidth of the digital voltage regulator controller.

9. The method of claim 1 , wherein the digital voltage regulator controller is a multi-phase digital voltage regulator controller and wherein the PID coefficients for one or more of the phases are determined using a nonlinear interpolation formula.

10. The method of claim 1 , further comprising:

transferring the PID coefficients to the digital controller via a hardware interface such that the digital voltage regulator controller uses the transferred PID coefficients to perform closed-loop impedance response compensation.

11. The method of claim 1 , further comprising:

storing the PID coefficients in memory such that he digital voltage regulator controller uses the stored PID coefficients to perform closed-loop impedance response compensation.

12. A non-transitory computer readable medium storing a computer program operable to determine control loop coefficients of a digital voltage regulator controller, the computer program comprising:

program instructions to determine PID (proportioal-integral-derivative) coefficients that meet gain and phase margin targets of a digital voltage regulator controller, as a function of a plurality of system parameters of the digital voltage regulator controller; and

program instructions to optimize one or more of the PID coefficients based on an output impedance closed loop response of the digital voltage regulator controller, wherein the one or more of the PID coefficients are optimized when a peak of the output impedance over frequency is minimized for frequencies below a bandwidth of the digital voltage regulator controller.

13. The non-transitory computer readable medium of claim 12 , wherein the program instructions to optimize one or more of the PID coefficients comprise program instructions to optimize a proportional gain and a derivative gain of the digital voltage regulator controller to flatten the output impedance closed loop response for frequencies below the bandwidth of the digital voltage regulator controller.

14. The non-transitory computer readable medium of claim 12 , wherein the PID coefficients are determined as a function of a switching frequency implemented by the digital voltage regulator controller in switching one or more power stages for driving a load, a number of active power stages controlled by the digital voltage regulator controller and a maximum number of power stages for which the digital voltage regulator controller is programmed to control.

15. The non-transitory computer readable medium of claim 12 , further comprising:

program instructions to determine a post-filter coefficient and the PID coefficients so that the gain and phase margin targets are satisfied, as a function of the system parameters; and

program instructions to optimize the post-filter coefficient and one or more of the PID coefficients based on the output impedance closed loop response of the digital voltage regulator controller, wherein the post-filter coefficient and the one or more of the PID coefficients are optimized when the peak of the output impedance over frequency is minimized for frequencies below the bandwidth of the digital voltage regulator controller.

16. The non-transitory computer readable medium of claim 12 , further comprising:

program instructions to determine an adaptive voltage position (AVP) filter coefficient that meets a maximum output impedance target of the digital voltage regulator controller; and

program instructions to optimize the AVP filter coefficient and one or more of the PID coefficients based on the output impedance closed loop response of the digital voltage regulator controller, wherein the AVP filter coefficient and the one or more of the PID coefficients are optimized when the peak of the output impedance over frequency is minimized for frequencies below the bandwidth of the digital voltage regulator controller.

17. The non-transitory computer readable medium of claim 12 , further comprising:

program instructions to determine a proportional gain and an integral gain for a current balance filter of the digital voltage regulator controller so that a bandwidth of the current balance filter is a fraction of the bandwidth of the digital voltage regulator controller.

18. The non-transitory computer readable medium of claim 12 , wherein the digital voltage regulator controller is a multi-phase digital voltage regulator controller and wherein the PID coefficients for one or more of the phases are determined using a nonlinear interpolation formula.

19. The non-transitory computer readable medium of claim 12 , further comprising program instructions to transfer the PID coefficient parameters from the computer program via a wired or wireless interface.