Abstract In recent years,as the technology of semiconductor has improved continuously,and the circuit design technology continues to progress,the IC industry has been growing quickly,the applications continue to be widely.But at the same,that require the circuits must have higher performances. In this work,the bandgap voltage reference is insensitive with the variations of power-supply,process,and temperature,with a high power supply rejection and low noise.There is a digital control circuit to modify the number of the PNP transistor arrays,as soft-trimming.The circuit produces a stable and accurate voltage to all other integrated circuits.The simulation results are given,the temperature coefficient is less than 28.38 ppm/C.When Vop is 3.3 V the Power-Supply Rejection is 88.9 dB at DC,it is 65 dB when VDD is 2.1 V.The integrated noise from 100 Hz to 100 kHz is 13 uVrms. In this work,there is an off-chip adjustable resistance for the voltage to current converter circuit.The circuit converts the output reference voltage from the bandgap voltage reference,to a stable current.As the power supply and process vary,the variation of the output current is less than 0.5%. Finally,there is a LDO(Low Dropout Regulator)voltage regulator,the compensation scheme provides a fast transient response for output voltage as the load change.Under the extreme condition,the phase margin is 40 deg. The other conditions,phase margin are more than 88 deg.The Power-Supply Rejection is 60 dB at DC when VDD is 3.3 V,it is 40 dB when VDD is 2.1 V.The integrated noise from 100 Hz to 100 kHz is 24 uVrms.The variation of the transient response of the output is less than 100 mV. This work bases on the SMIC 0.18-um CMOS process to simulate. Keywords:Bandgap Voltage Reference,LDO,High PSRR,Low Noise, Soft-trimming,Fast Transient Response Classification Code:TN432 33 Abstract In recent years, as the technology of semiconductor has improved continuously, and the circuit design technology continues to progress, the IC industry has been growing quickly, the applications continue to be widely. But at the same, that require the circuits must have higher performances. In this work, the bandgap voltage reference is insensitive with the variations of power-supply, process, and temperature, with a high power supply rejection and low noise. There is a digital control circuit to modify the number of the PNP transistor arrays, as soft-trimming. The circuit produces a stable and accurate voltage to all other integrated circuits. The simulation results are given, the temperature coefficient is less than 28.38 ppm/℃. When VDD is 3.3 V the Power-Supply Rejection is 88.9 dB at DC, it is 65 dB when VDD is 2.1 V. The integrated noise from 100 Hz to 100 kHz is 13 μVrms. In this work, there is an off-chip adjustable resistance for the voltage to current converter circuit. The circuit converts the output reference voltage from the bandgap voltage reference, to a stable current. As the power supply and process vary, the variation of the output current is less than 0.5 ‰. Finally, there is a LDO(Low Dropout Regulator) voltage regulator, the compensation scheme provides a fast transient response for output voltage as the load change. Under the extreme condition, the phase margin is 40 deg. The other conditions, phase margin are more than 88 deg. The Power-Supply Rejection is 60 dB at DC when VDD is 3.3 V, it is 40 dB when VDD is 2.1 V. The integrated noise from 100 Hz to 100 kHz is 24 μVrms. The variation of the transient response of the output is less than 100 mV. This work bases on the SMIC 0.18-μm CMOS process to simulate. Keywords: Bandgap Voltage Reference，LDO，High PSRR，Low Noise， Soft-trimming，Fast Transient Response Classification Code: TN432