Research And Realization Of CMOS Bandgap Reference Source

A voltage reference source provides high-precision voltage reference for other functional modules in the circuit system, or high-precision current reference can transformed from it. It is a very important module in the analog integrated circuits and mixed-signal integrated circuits design. The output signal of the voltage reference is stable, and it is independent of supply voltage, temperature and process. This thesis designed three bandgap references on the basis of the research of bandgap reference theory.The first bandgap reference is used in the DAC. The core of the reference circuit used PNP transistors in series to reduce amplifier offset, and the amplifier used the folded cascode structure to get high input swing, and the bias circuit used the low-voltage cascode current mirror structure and the self-biased low-voltage cascode current mirror structure to bias the entire reference circuit. In the thesis, we simulated the reference circuit by using the Hspice simulation tool based on the SMIC 0.35μm process. The simulation results are that the temperature coefficient of the references is 15.7 ppm /℃when temperature scaned from -40℃to 100℃,and the power supply rejection ratio is 75 dB at 1 kHz and there is still 58 dB at10 kHz. The simulation results showed that the reference circuit can work normally in the DAC system.The second bandgap reference is applied to the LDO. The reference circuit used cascode current mirror structure to obtain high power supply rejection ratio. In the thesis, we simulated the reference circuit by using the Hspice simulation tool based on the SMIC 0.35μm process. The simulation results are that the power supply rejection ratio is 80dB at 1kHz, and the temperature coefficient of the reference is 24ppm /℃, and the quiet current is less than 4μA. The simulation results showed that the reference circuit can work normally in the LDO system.The third bandgap reference is designed for low-voltage-power-supply system with high precision requirement. In the thesis, we simulated the reference circuit by using the Hspice simulation tool based on the SMIC 0.35μm process. The simulation results are that when the temperature scans from -40℃to 100℃, the reference's output changes only 0.3 mV and the references temperature coefficient is only 2.14 ppm /℃,and the reference circuit can work normally when the power supply changes from 1.2V to 3 V. The simulation results showed that the reference circuit can work normally in the low-voltage-power-supply system with high precision requirement.