A charge pump circuit operable to output a bipolar output voltage, comprising: an input node and a reference node for connection to an input voltage; a pair of output nodes (VP,VN) arranged to output the bipolar output voltage; two pairs of flying capacitor nodes (CF1A, CF1 B; CF2A,CF2B); a network of switching paths for interconnecting said nodes; and a controller operable to control the network of switching paths to selectively provide a first mode and a second mode when in use with only two flying capacitors connected to the flying capacitor nodes by sequencing the network of switching paths through cycles of switching states, wherein each of the first and second modes produce a non-zero bipolar output voltage at said pair of output nodes, the bipolar output voltage in the first mode being different to that in the second mode; characterised in that the first mode corresponds to a bipolar output voltage of +/-3VV, where VV is the input voltage; and wherein in use with a first flying capacitor connected to first and second flying capacitor nodes (CF1 A, CF1 B) and a second flying capacitor connected to the third and fourth flying capacitor nodes (CF2A, CF2B), a first reservoir capacitor connected between the first output node and the reference node and a second reservoir capacitor connected between the reference node and the second output node, the controller is operable to control the network of switching paths such that in a first switching state the first flying capacitor node (CF1A) is connected to the input node and the second flying capacitor node (CF1 B) is connected to the reference node, in a second state, the second flying capacitor node (CF1 B) is connected to the input node, the first flying capacitor node (CF1 A) is connected to the third flying capacitor node (CF2A), and the fourth flying capacitor node (CF2B) is connected to the reference node; in a third state the network of switching paths is controlled to connect the first and second flying capacitors in series between the first output node and the reference node; and in a fourth state the network of switching paths is controlled to connect the first and second flying capacitors in series between the reference node and the second output node. an input node and a reference node for connection to an input voltage; a pair of output nodes (VP,VN) arranged to output the bipolar output voltage; two pairs of flying capacitor nodes (CF1A, CF1 B; CF2A,CF2B); a network of switching paths for interconnecting said nodes; and a controller operable to control the network of switching paths to selectively provide a first mode and a second mode when in use with only two flying capacitors connected to the flying capacitor nodes by sequencing the network of switching paths through cycles of switching states, wherein each of the first and second modes produce a non-zero bipolar output voltage at said pair of output nodes, the bipolar output voltage in the first mode being different to that in the second mode; characterised in that the first mode corresponds to a bipolar output voltage of +/-3VV, where VV is the input voltage; and wherein in use with a first flying capacitor connected to first and second flying capacitor nodes (CF1 A, CF1 B) and a second flying capacitor connected to the third and fourth flying capacitor nodes (CF2A, CF2B), a first reservoir capacitor connected between the first output node and the reference node and a second reservoir capacitor connected between the reference node and the second output node, the controller is operable to control the network of switching paths such that in a first switching state the first flying capacitor node (CF1A) is connected to the input node and the second flying capacitor node (CF1 B) is connected to the reference node, in a second state, the second flying capacitor node (CF1 B) is connected to the input node, the first flying capacitor node (CF1 A) is connected to the third flying capacitor node (CF2A), and the fourth flying capacitor node (CF2B) is connected to the reference node; in a third state the network of switching paths is controlled to connect the first and second flying capacitors in series between the first output node and the reference node; and in a fourth state the network of switching paths is controlled to connect the first and second flying capacitors in series between the reference node and the second output node.