Abstract： Based on the actual design requirements of DC-DC chip circuit, this paper designs a bandgap reference circuit with an input voltage range of 2.5~15 V. Through the design of the pre-regulator circuit, the reference voltage output by the bandgap reference core is transformed into a stable current source, and the negative feedback structure is formed to provide a power supply voltage for the bandgap reference core itself, thus increasing the upper limit of the power supply voltage range. Through the voltage selection circuit, the bandgap reference core is directly powered by the power supply voltage when the power supply voltage is lower than 5 V, which broadens the lower limit of the power supply voltage range. At the same time, the pre-regulator circuit and the cascode structure in the bandgap reference core brings good power supply rejection performance to this circuit. This design is based on 0.25μm BCD process, and the schematic diagram, layout design and simulation of the circuit are completed. The results show that this design can output a stable voltage of 0.8 V in the temperature range of -55℃~125℃, and the temperature coefficient is 7.78 ppm/℃. At low frequency, the PSR reaches 159 dB, and the line sensitivity is 0.001 2%.
Key words : bandgap reference；PSR；pre-regulator；voltage selection circuit
