Study And Design Of Bandgap Reference With High-order Curvature Compensation Based On Switched-capacitor

With the development of biomedical implantable microchips,wearable microsensors and wireless sensor networks,it is a certain progress and representative to design high-precision,low-power,and highly-integrated power chips.Bandgap reference(BGR)is an essential block in the integrated circuits and widely used in various analog ICs,such as biomedical devices,wireless energy harvesting and digital low dropout regulator.However,the supply voltage of the traditional BGR is affected by the turn-on voltage of the bipolar transistor,resulting in its minimum supply voltage greater than 700 mV.And thus,it limits the application of BGR in low supply voltage,low-power systems.This thesis presents a switched-capacitor BGR with high order compensation based on 0.18?m CMOS process.The proposed BGR is mainly composed of a switched-capacitor clamp,a high-order curvature compensation and a linear combination circuit.In this thesis,a switched-capacitor clamp circuit is employed to drive a bipolar transistor with a low supply voltage.By changing the number of bipolar transistors,complementary-toabsolute-temperature(CTAT)voltages are obtained with different slopes.Therefore,proportional to absolute temperature(PTAT)voltage are further obtained without amplifier as well.In order to improve the temperature stability,a high-order curvature compensation circuit is used to reduce the temperature coefficient(TC),which takes advantages of CMOS characters work in the sub-threshold region.Additionally,the voltages of the CTAT,PTAT and high-order compensation circuits are linear combinate,achieving a low TC through linear combination circuit.For further improvement,a low leakage switch and trimming circuit are applied to improve the accuracy of the proposed BGR.The simulation results show that the BGR could operate on a 0.45 V supply voltage.For supply voltages ranging from 0.45 to 3V the power consumption is 66.5nW,and the temperature coefficient at 0.5V supply voltage is 27.1ppm/°C across a temperature range of-20 to 100°C and a mean line sensitivity of 2.5%.In addition,the chip area is 380?m.Compared with related works in recent years,TC has been reduced by 30% under the same process conditions,which is in line with the design requirements of low-power,high-precision systems.