Research On CMOS Band Gap Reference

In recent years, as the level of semiconductor process and the technology of integrated circuit design have improved continuously, the IC industry has been growing rapidly and the application continues to be widely. But at the same time, the performance requirements must be higher. The reference supplies stable and accurate voltage/current for other circuit parts and its performance affects the entire system circuit.In this paper, 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 a soft-trimming to make the voltage reference more stable and accurate. The simulation results are given, the temperature coefficient is less than4ppm/℃. When VDD is3.3V the PSRR is88.9dB at DC, it is65dB at2.1Vat DC. The integrated noise from100Hz to100kHz is16.8uVrms.In this paper, the voltage-current conversion circuit used to convert the reference voltage into a stable and accurate output current covers the Op Amp, controllable resistances and current mirror.In this paper, the temperature sensor circuit constitute by the Op Amp and the temperature sensor core circuit. It is used to compare the output voltage with the temperature.Finally, this paper gives the layout design of the three circuits respectively. The post-simulation results of each part are given, the temperature coefficient is less than4ppm/℃. When VDD is3.3V the PSRR is88.9dB at DC, it is65dB at2.1Vat DC. The integrated noise from100Hz to100kHz is16.8μVrms.The simulation of this paper is based on the TSMC0.18-μm CMOS process. The power consumption is340mW at2.1V and540mW at3.3V.