An implantable pulse generator for generating electrical pulses for stimulating tissue of a patient, comprising: pulse generating circuitry (309, 310, 311) for generating pulses and delivering the pulses to outputs of the implantable pulse generator; a controller (204, 206) for controlling the pulse generating circuitry; wherein the pulse generating circuitry comprises a voltage multiplier for multiplying a battery voltage; wherein the controller controls the pulse generator circuitry to generate a first pulse for stimulation of the patient using a first voltage from the voltage multiplier and controls the pulse generator circuitry to generate a second pulse to discharge output capacitors of residual charge from the first pulse using a second voltage from the voltage multiplier; and wherein the controller uses different settings, for a current control circuit that controls a current of an output pulse, for the first and second pulses; characterised in that the voltage multiplier comprises including multiple outputs, wherein a first output (V MULT) of the multiple outputs provides a voltage that is programmably selectable from a plurality of voltages including non-integer multiples of the battery voltage, wherein a second output (V BATT, 2V BATT) of the multiple outputs provides a voltage that is a fixed multiple of the battery voltage; wherein the controller controls the pulse generator circuitry to generate the first pulse for stimulation of the patient using a first output of the multiple outputs and controls the pulse generator circuitry to generate the second pulse to discharge output capacitors of residual charge from the first pulse using a second output of the multiple outputs. pulse generating circuitry (309, 310, 311) for generating pulses and delivering the pulses to outputs of the implantable pulse generator; a controller (204, 206) for controlling the pulse generating circuitry; wherein the pulse generating circuitry comprises a voltage multiplier for multiplying a battery voltage; wherein the controller controls the pulse generator circuitry to generate a first pulse for stimulation of the patient using a first voltage from the voltage multiplier and controls the pulse generator circuitry to generate a second pulse to discharge output capacitors of residual charge from the first pulse using a second voltage from the voltage multiplier; and wherein the controller uses different settings, for a current control circuit that controls a current of an output pulse, for the first and second pulses; characterised in that the voltage multiplier comprises including multiple outputs, wherein a first output (V MULT) of the multiple outputs provides a voltage that is programmably selectable from a plurality of voltages including non-integer multiples of the battery voltage, wherein a second output (V BATT, 2V BATT) of the multiple outputs provides a voltage that is a fixed multiple of the battery voltage; wherein the controller controls the pulse generator circuitry to generate the first pulse for stimulation of the patient using a first output of the multiple outputs and controls the pulse generator circuitry to generate the second pulse to discharge output capacitors of residual charge from the first pulse using a second output of the multiple outputs.