A charge pump circuit for generating a negative voltage has: a clock generator arranged to output at least one clock signal; a switched capacitor voltage inverter circuit including capacitive elements wherein the switched capacitor voltage inverter circuit receives the at least one clock signal and generates a negative voltage therefrom. The charge pump circuit further has a regulation control loop providing a feedback path from an output of the switched capacitor voltage inverter circuit to a supply input of the switched capacitor voltage inverter circuit, and an output arranged to output a generated negative voltage. The feedback path has an operational amplifier configured to generate a maximum charging supply voltage from a fed back level-shifted negative voltage and apply the maximum charging supply voltage to the input supply of the switched capacitor voltage inverter to charge at least one of the capacitive elements during a loop start up.