Switching Regulator Control with Nonlinear Feed-Forward Correction

1 . A method of controlling a power stage of a switching regulator, the method comprising:

setting a duty cycle for the power stage using feed-forward control so that the power stage produces an output voltage based on an input voltage and a reference voltage provided to the switching regulator; and

adjusting the feed-forward control to counteract the effect of one or more nonlinearities of the switching regulator on the output voltage.

2 . The method according to claim 1 , wherein adjusting the feed-forward control comprises:

calculating a feed-forward control value based on the input voltage and the reference voltage; and

scaling the feed-forward control value responsive to a nonlinearity of the switching regulator.

3 . The method according to claim 2 , wherein scaling the feed-forward control value responsive to a nonlinearity of the switching regulator comprises:

calculating a gain term as a function of one or more system variables of the switching regulator and a corresponding control parameter for each system variable; and

multiplying the feed-forward control value by the gain term.

4 . The method according to claim 1 , wherein adjusting the feed-forward control comprises:

calculating a feed-forward control value based on the input voltage and the reference voltage; and

adding or subtracting a bias term to the feed-forward control value responsive to a nonlinearity of the switching regulator.

5 . The method according to claim 4 , further comprising calculating the bias gain term as a function of one or more system variables of the switching regulator and a corresponding control parameter for each system variable.

6 . The method according to claim 1 , wherein the feed-forward control is adjusted responsive to a system variable of the switching regulator violating a control parameter.

7 . The method according to claim 6 , wherein the feed-forward control adjustment is based on one or more programmable control parameters.

8 . The method according to claim 6 , wherein the system variable corresponds to a power state of the switching regulator, a phase current of the power stage, the output voltage, the input voltage, a number of active phases of the power stage, or operating temperature of the switching regulator.

9 . The method according to claim 1 , wherein the power stage comprises a high-side transistor and a low-side transistor connected to an inductor, and wherein adjusting the feed-forward control comprises increasing the duty cycle for the power stage during a current cycle of the power stage if the high-side transistor turned on while the inductor current was negative during an immediately preceding cycle and the high-side transistor is expected to turn on while the inductor current is positive during the current cycle.

10 . A switching regulator, comprising:

an power stage operable to produce an output voltage; and

a controller operable to set a duty cycle for the power stage based on feed-forward control so that the power stage produces the output voltage as a function of an input voltage and a reference voltage provided to the switching regulator, and adjust the feed-forward control to counteract the effect of one or more nonlinearities of the switching regulator on the output voltage.

11 . The switching regulator according to claim 10 , wherein the controller is operable to calculate a feed-forward control value based on the input voltage and the reference voltage, and scale the feed-forward control value responsive to a nonlinearity of the switching regulator.

12 . The switching regulator according to claim 11 , wherein the controller is operable to calculate a gain term as a function of one or more system variables of the switching regulator and a corresponding control parameter for each system variable, and multiply the feed-forward control value by the gain term.

13 . The switching regulator according to claim 10 , wherein the controller is operable to calculate a feed-forward control value based on the input voltage and the reference voltage, and add or subtract a bias term to the feed-forward control value responsive to a nonlinearity of the switching regulator.

14 . The switching regulator according to claim 13 , wherein the controller is operable to calculate the bias gain term as a function of one or more system variables of the switching regulator and a corresponding control parameter for each system variable.

15 . The switching regulator according to claim 10 , wherein the controller is operable to adjust the feed-forward control responsive to a system variable of the switching regulator violating a control parameter.

16 . The switching regulator according to claim 15 , wherein the feed-forward control adjustment is based on one or more programmable control parameters.

17 . The switching regulator according to claim 15 , wherein the system variable corresponds to a power state of the switching regulator, a phase current of the power stage, the output voltage, the input voltage, a number of active phases of the power stage, or operating temperature of the switching regulator.

18 . The switching regulator according to claim 10 , wherein the controller is operable to adjust the feed-forward control responsive to a nonlinearity of the switching regulator based on information obtained from a look-up table and associated with the nonlinearity.

19 . The switching regulator according to claim 10 , wherein the controller is operable to be programmed to adjust the feed-forward control to counteract a nonlinearity of the switching regulator.

20 . The switching regulator according to claim 19 , wherein the controller is operable to:

sweep a load current supplied by the power stage to identify a control parameter at which a nonlinearity of the switching regulator causes a bandwidth of the switching regulator to degrade by more than a target amount;

set a gain value so that the effect of the nonlinearity is minimized; and

adjust the feed-forward control based on the gain value when the load current drops below the control parameter during operation of the switching regulator.

21 . A switching regulator, comprising:

an power stage operable to produce an output voltage, the power stage comprising a high-side transistor and a low-side transistor connected to an inductor; and

a controller operable to increase a duty cycle for the power stage during a current cycle of the power stage if the high-side transistor turned on while the inductor current was negative during an immediately preceding cycle and the high-side transistor is expected to turn on while the inductor current is positive during the current cycle.