A sub-bandgap reference voltage generator includes a reference current generator generating a reference current (proportional to absolute temperature), a voltage generator generating an input voltage (proportional to absolute temperature) from the reference current, and a differential amplifier. The differential amplifier is biased by the reference current and has an input receiving the input voltage and a resistor generating a voltage proportional to absolute temperature summed with the input voltage to produce a temperature insensitive output reference voltage. The reference current generator may generate the reference current as a function of a difference between bias voltages of first and second transistors. The voltage generator may generate the input voltage by applying the current proportional to absolute temperature through a plurality of transistors coupled in series between the bias voltage of the second transistor and ground, and tapping a node between given adjacent ones of the plurality of transistors.