A reference voltage generating circuit, comprising: a proportional to absolute temperature, PTAT, servo loop comprising a first operational amplifier; a first diode-connected transistor device with a first current density coupled to a first input of the first operational amplifier and a second diode-connected transistor device with a second current density different than the first current density coupled to a second input of the first operational amplifier; a first MOS transistor coupled to an output of the first operational amplifier and connected to the first transistor device (Ql), a second MOS transistor coupled to the first MOS transistor, a third transistor coupled to the second MOS transistor to output a first current (iPtat); and a first resistor coupled to the second transistor device to output a first voltage, wherein other end of the first resistor is connected to the second MOS transistor and the second input of the first operational amplifier; a complementary to absolute temperature, CTAT, servo loop comprising a second operational amplifier comprising a first input that is connected to the first resistor to receive the first voltage; a fourth MOS transistor coupled to an output of the second operational amplifier and connected to a second input of the second operational amplifier; and a fifth MOS transistor coupled to the fourth MOS transistor to output a second current (iCtat) based on the first voltage; and the reference voltage generating circuit also comprising a second resistor coupled to the PTAT servo loop, the CTAT servo loop, to receive, respectively, the first and second current, and to ground, wherein a voltage across the second resistor is a reference voltage (vBgf), a proportional to absolute temperature, PTAT, servo loop comprising a first operational amplifier; a first diode-connected transistor device with a first current density coupled to a first input of the first operational amplifier and a second diode-connected transistor device with a second current density different than the first current density coupled to a second input of the first operational amplifier; a first MOS transistor coupled to an output of the first operational amplifier and connected to the first transistor device (Ql), a second MOS transistor coupled to the first MOS transistor, a third transistor coupled to the second MOS transistor to output a first current (iPtat); and a first resistor coupled to the second transistor device to output a first voltage, wherein other end of the first resistor is connected to the second MOS transistor and the second input of the first operational amplifier; a complementary to absolute temperature, CTAT, servo loop comprising a second operational amplifier comprising a first input that is connected to the first resistor to receive the first voltage; a fourth MOS transistor coupled to an output of the second operational amplifier and connected to a second input of the second operational amplifier; and a fifth MOS transistor coupled to the fourth MOS transistor to output a second current (iCtat) based on the first voltage; and the reference voltage generating circuit also comprising a second resistor coupled to the PTAT servo loop, the CTAT servo loop, to receive, respectively, the first and second current, and to ground, wherein a voltage across the second resistor is a reference voltage (vBgf),