A reference voltage generator having a multi-slope temperature characteristic and being integratable monolithically, for use in a voltage regulator, characterized in that it comprises a circuit means effective to generate a first voltage having a thermal drift coefficient of zero and at least second and third voltages having predetermined respective non-zero thermal drift coefficients, a first voltage divider and at least first and second voltage-follower circuits which are respectively applied said first, second and third voltages, a unidirectional conduction amplifier circuit having an input terminal connected to an intermediate node of the first voltage divider and an output terminal connected through a first resistive element to an output circuit node which is coupled to an output terminal of the reference voltage generator, also connected to said output circuit node through a second and a third resistive element, respectively, being respective output terminals of said at least first and second voltage follower circuits.