Controlling a skew time of switches of a switching regulator
Embodiments for methods and apparatuses for controlling a skew time of switches of a switching voltage regulator are disclosed. One method includes generating a switching voltage through closing and opening of a series switch and a shunt switch as controlled by a series switch control signal and a shunt switch control signal. An error signal is generated that is proportional to a relative displacement of an on-interval of the series switch and an off-interval of the shunt switch. A relative delay of the series switch control signal and the shunt switch control signal is adjusted based on the error signal, and a regulated output voltage is generated based upon the switching voltage.
1. A method of controlling a skew time of switches of a switching voltage regulator comprising:
generating a switching voltage through closing and opening of a series switch and a shunt switch as controlled by a series switch control signal and a shunt switch control signal;
generating an error signal proportional to a relative displacement of an on-interval of the series switch and an off-interval of the shunt switch, wherein the error signal is generated based on a gate voltage of the series switch and a gate voltage of the shunt switch;
adjusting a relative delay of the series switch control signal and the shunt switch control signal based on the error signal; and
generating a regulated output voltage based upon the switching voltage.
2. The method of claim 1 , wherein series switch control signal and a shunt switch control signal comprise dead times in which the series switch and the shunt switch are turned off, wherein a first dead time (DT 1 ) is defined by a period of time in which the shunt switch has just entered its off-interval, but the series switch has not yet entered its on-interval, and a second dead time (DT 2 ) is defined by a period of time in which the series switch has just entered its off-interval and the shunt switch has not yet entered its on-interval.
3. The method of claim 2 , wherein the error signal is dependent upon the first dead time (DT 1 ) and the second dead time (DT 2 ).
4. The method of claim 3 , wherein a sign of the error signal changes when a relative magnitude of DT 1 changes from less than to greater than DT 2 .
5. The method of claim 3 , wherein the error signal reaches a target value when the on-interval of the series switch is delayed relative to the off-interval of the shunt switch by a desired amount.
6. The method of claim 2 , wherein the error signal is minimized when DT 1 is approximately equal to DT 2 .
7. The method of claim 2 , further comprising adjusting the error signal with an offset to intentionally adjust DT 1 to not be equal to DT 2 .
8. The method of claim 7 , wherein the offset is adaptively selected to improve efficiency of the switching converter by adjusting DT 1 and DT 2 , wherein a sum of DT 1 +DT 2 is a fixed value.
9. The method of claim 2 , wherein the error signal comprises pulses corresponding to the dead times DT 1 , DT 2 .
10. The method of claim 2 , wherein the error signal is generated by a current skew detector, the current skew detector comprising a dual phase detector, a charge pump circuit, and a difference circuit.
11. The method of claim 10 , wherein the current skew detector further comprises an input level shifter for one of the series switch control signal and a shunt switch control signal, and an input time delay block for the other of the series switch control signal and a shunt switch control signal.
12. The method of claim 10 , wherein the error signal is generated by the charge pump, and the charge pump is only active during the dead times DT 1 , DT 2 .
13. The method of claim 10 , wherein the dual phase detector comprises symmetric interval detection for providing insensitivity of the error signal to asymmetry of rising and falling edges of the series switch control signal and a shunt switch control signal, and to inherent delays within the dual phase detector.
14. The method of claim 1 , wherein the error signal is generated by a current skew detector, the current skew detector comprising a switched signal phase detector, a charge pump circuit, and a low pass filter.
15. A switching voltage regulator, comprising:
a series switch;
a shunt switch;
a switching controller operative to generating a switching voltage through closing and opening of the series switch and the shunt switch as controlled by a series switch control signal and a shunt switch control signal;
a skew detector operative to generate an error signal proportional to a relative displacement of an on-interval of the series switch and an off-interval of the shunt switch;
the switch controller further operative to adjust a relative delay of the series switch control signal and the shunt switch control signal based on the error signal, wherein the error signal is generated based on a gate voltage of the series switch and a gate voltage of the shunt switch; and
the voltage regulator operative to generate a regulated output voltage based upon the switching voltage.
16. The switching voltage regulator of claim 15 , wherein series switch control signal and a shunt switch control signal comprise dead times in which the series switch and the shunt switch are turned off, wherein a first dead time (DT 1 ) is defined by a period of time in which the shunt switch has just entered its off-interval, but the series switch has not yet entered its on-interval, and a second dead time (DT 2 ) is defined by a period of time in which the series switch has just entered it off-interval and the shunt switch has not yet entered its on-interval.
17. The switching voltage regulator of claim 16 , wherein the error signal is dependent upon the first dead time (DT 1 ) and the second dead time (DT 2 ).
18. The switching voltage regulator of claim 16 , wherein the error signal is minimized when DT 1 is approximately equal to DT 2 .
19. The switching voltage regulator of claim 16 , further comprising adjusting the error signal with an offset to intentionally adjust DT 1 to not be equal to DT 2 .
20. The switching voltage regulator of claim 15 , wherein the skew detector, the current skew detector comprising a dual phase detector, a charge pump circuit, and a difference circuit.
21. The switching voltage regulator of claim 20 , wherein the skew detector further comprises an input level shifter for one of the series switch control signal and a shunt switch control signal, and an input time delay block for the other of the series switch control signal and a shunt switch control signal.
22. The switching voltage regulator of claim 20 , wherein the dual phase detector comprises symmetric interval detection for providing insensitivity of the error signal to asymmetry of rising and falling edges of the series switch control signal and a shunt switch control signal.