Charge pump circuit

A charge pump circuit operable to output a bipolar output voltage, comprising:

• an input node for connection to an input voltage;
• a first output node and a second output node for outputting the bipolar output voltage;
• two pairs of flying capacitor nodes;
• a network of switching paths for interconnecting said nodes;
• and
• a controller operable, when in use with two flying capacitors connected to the flying capacitor nodes and with first and second reservoir capacitors connected to the first and second output nodes respectively, in at least a first mode to control the network of switching paths to repeatedly cycle between a plurality of switch states;
• wherein said plurality of switch states of switch states includes at least one switch state for charging the first reservoir capacitor and at least one switch state for charging the second reservoir capacitor, and
• wherein said plurality of switch states is selected to provide a first bipolar output voltage that comprises one of +/−3*VV, +/−2*VV, +/−VV/3, +/−VV/4, +/−VV/5 or +/−VV/6 where VV is the input voltage;
• and
• wherein the controller is configured such that the rate of occurrence of said switch states for charging the first or second reservoir capacitors is variable.

A charge pump circuit comprising:

• an input node for connection to an input voltage;
• first and second output nodes for outputting an bipolar output voltage;
• two pairs of flying capacitor nodes;
• a network of switching paths for interconnecting said nodes;
• and
• a controller operable, in use with two flying capacitors connected to the flying capacitor nodes and with first and second reservoir capacitors connected to the first and second output nodes respectively, in at least a first mode to control the network of switching paths in a plurality of switch states to provide a first bipolar output voltage that comprises one of +/−3*VV, +/−2*VV, +/−VV/3, +/−VV/4, +/−VV/5 or +/−VV/6 where VV is the input voltage;
• wherein the controller is configured to control said switch states based on an indication of voltage droop of said first and second reservoir capacitors to vary a rate of occurrence of a switch state for recharging at least one of said first and second reservoir capacitors.