A voltage detector comprising: a first voltage reference generator for generating a first voltage reference signal; a second voltage reference generator for generating a second voltage reference signal, wherein the first voltage reference signal is higher than the second voltage reference signal; a trigger, powered by an input signal to the voltage detector, and having an input for receiving either the first or second voltage reference signal and an output for generating a detection signal; and a switch for selectively connecting the input of the trigger to the first or second voltage reference signal, wherein: the switch is operative to connect the input of the trigger to the first voltage reference signal when the detection signal output by the trigger is low and is operative to connect the input of the trigger to the second voltage reference signal when the detection signal output by the trigger is high; and the first and second voltage reference generators (350, 360) of the voltage detector each comprise a first transistor, arranged to have a zero gate-source voltage, and a second transistor, connected as a diode, connected in series between the input signal and a common reference, wherein the first transistor has a lower gate threshold than the second transistor; characterized in that the voltage detector comprises a third voltage reference generator for generating a third voltage reference signal, wherein the third voltage reference generator is configured to output the third voltage reference signal to the first and second voltage reference generators (350, 360), and the third voltage reference signal sets the body bias of the first transistor of each of the first and second reference generators (350, 360). a first voltage reference generator for generating a first voltage reference signal; a second voltage reference generator for generating a second voltage reference signal, wherein the first voltage reference signal is higher than the second voltage reference signal; a trigger, powered by an input signal to the voltage detector, and having an input for receiving either the first or second voltage reference signal and an output for generating a detection signal; and a switch for selectively connecting the input of the trigger to the first or second voltage reference signal, wherein: the switch is operative to connect the input of the trigger to the first voltage reference signal when the detection signal output by the trigger is low and is operative to connect the input of the trigger to the second voltage reference signal when the detection signal output by the trigger is high; and the first and second voltage reference generators (350, 360) of the voltage detector each comprise a first transistor, arranged to have a zero gate-source voltage, and a second transistor, connected as a diode, connected in series between the input signal and a common reference, wherein the first transistor has a lower gate threshold than the second transistor; characterized in that the voltage detector comprises a third voltage reference generator for generating a third voltage reference signal, wherein the third voltage reference generator is configured to output the third voltage reference signal to the first and second voltage reference generators (350, 360), and the third voltage reference signal sets the body bias of the first transistor of each of the first and second reference generators (350, 360). the switch is operative to connect the input of the trigger to the first voltage reference signal when the detection signal output by the trigger is low and is operative to connect the input of the trigger to the second voltage reference signal when the detection signal output by the trigger is high; and the first and second voltage reference generators (350, 360) of the voltage detector each comprise a first transistor, arranged to have a zero gate-source voltage, and a second transistor, connected as a diode, connected in series between the input signal and a common reference, wherein the first transistor has a lower gate threshold than the second transistor; characterized in that the voltage detector comprises a third voltage reference generator for generating a third voltage reference signal, wherein the third voltage reference generator is configured to output the third voltage reference signal to the first and second voltage reference generators (350, 360), and the third voltage reference signal sets the body bias of the first transistor of each of the first and second reference generators (350, 360).