Digital slope control for switched capacitor dc-dc converter
Representative implementations of devices and techniques minimize switching losses in a switched capacitor dc-dc converter. The slope of the charging and/or discharging phase may be modified, smoothing the transitions from charge to discharge and/or discharge to charge of the switched capacitor.
1. A system comprising:
a direct current to direct current converter (dc-dc converter), including:
an energy storage element; and
a plurality of switches coupled to the energy storage element; and
a switch control element arranged to output a conductance adjustment signal to one or more of the plurality of switches, based on a load coupled to an output of the dc-dc converter;
a slope control element arranged to control a rate of change of the conductance adjustment signal, the control of the rate of change of the conductance being provided by a smoothed version of the conductance adjustment signal; and
wherein the slope control element includes a low pass filter arranged to receive a digital word representing a conductance value and output a smoothed slope control signal, the smoothed slope control signal being the smoothed version of the conductance adjustment signal.
2. The system of claim 1 , wherein the slope control element is arranged to regulate a rate of change of at least one of a charge phase and a discharge phase of the energy storage element.
3. The system of claim 1 , wherein the switch control element comprises a digital to analog converter (DAC) arranged to output the conductance adjustment signal to the one or more of the plurality of switches.
4. A system comprising:
a direct current to direct current converter (dc-dc converter), including:
an energy storage element; and
a plurality of switches coupled to the energy storage element, one or more of the plurality of switches comprising a set of sub-switches;
a switch control element arranged to control a switch state of one or more of the set of sub-switches, based on a load coupled to an output of the dc-dc converter;
a slope control element arranged to control a rate of change of the switch state of the one or more of the set of sub-switches, the slope control element to control the rate of change of the switch state of the one or more of the set of sub-switches in accordance with a smoothed version of a conductance adjustment signal; and
wherein the slope control element includes a low pass filter arranged to receive a digital word representing a conductance value and output a smoothed slope control signal to the switch control element, the smoothed slope control signal being the smoothed version of the conductance adjustment signal.
5. The system of claim 4 , wherein each of the sub-switches of the set of sub-switches has a maximum conductance substantially equivalent to a maximum conductance of the one or more of the plurality of switches divided by a number of sub-switches in the set.
6. The system of claim 4 , wherein the slope control element is arranged to regulate a rate of change of at least one of a charge phase and a discharge phase of the energy storage element.
7. The system of claim 4 , wherein the switch control element controls the switch state of the one or more of the set of sub-switches based on a digital word received at the switch control element.
8. The system of claim 7 , wherein the digital word represents a conductance value for the one or more of the plurality of switches comprised of the set of sub-switches.
9. The system of claim 7 , wherein the digital word represents which sub-switches of the set of sub-switches are in an open state, and which sub-switches of the set of sub-switches are in a closed state.
10. The system of claim 7 , wherein the switch control element is arranged to map bits of the digital word to sub-switches of the set of sub-switches.
11. The system of claim 10 , further comprising control lines, and wherein the switch control element is arranged to map the bits of the digital word to the sub-switches of the set of sub-switches via the control lines.
12. The system of claim 7 , wherein the slope control element is arranged to insert delays configured to delay switching of one or more sub-switches of the set of sub-switches.
13. The system of claim 7 , further comprising control lines mapping bits of the digital word to sub-switches of the set of sub-switches, and wherein the slope control element is arranged to insert one or more delay elements at the control lines during each clock cycle to delay switching of the sub-switches based on a number of delay elements inserted.
14. The system of claim 13 , wherein the slope control element is arranged to insert sets of ascending or descending numbers of delay elements at sets of adjacent control lines.