Design And Improvement Of Bandgap Reference With Low Temperature Coefficient

Nowadays,integrated circuit(IC)plays an important role in modern electronics.As the core component of many analog circuits and mixed-signal circuits,the reference determines whether the chip can work reliably.From the perspective of market demand and chip optimization,it is of great significance to research its key technologies and performance optimization.Based on the in-depth research of the working principle and control method of the traditional reference,this paper focuses on the two key technologies of the bandgap reference.The lower temperature coefficient is carried out in a wide temperature range of-40 to 150?at a power supply voltage of 3V in the voltage-type and the current-type CMOS bandgap reference,and the operational amplifier is improved with low mismatch.The main research contents of this paper are summarized as follows:1.Two key technologies of the bandgap reference are researched:After analyzing the temperature characteristics and offset of the bandgap reference,four common temperature compensation technologies and three offset elimination technologies have been researched and compared in this paper.2.The voltage-type and current-type CMOS bandgap reference with lower temperature coefficient have been designed:In the voltage-type CMOS bandgap reference,the CTAT voltage V_BE of the transistor is detected,then through the sink/source current selection circuit,the temperature coefficient of output voltage is reduced to 4.11 ppm/°C within-40?150°C by using piece-wise curve rectification method.In the current-type CMOS bandgap reference,After the first-order compensation,the output temperature characteristic curve has two situations:convex and concave.By detecting CTAT and PTAT currents,then the current subtraction circuit is used to sink/source the output current to achieve the lower temperature coefficient.Finally,the temperature coefficient is reduced to 2.19 ppm/?and 2.55 ppm/?within-40?150?.3.The voltage-type and current-type CMOS bandgap reference with lower mismatch have been designed:In the voltage-type CMOS bandgap reference,low mismatch is achieved through chopper technology,and the final mismatch of output voltage is only 1.03m V within1sigma.In the current-type CMOS bandgap reference,the device size and circuit structure of the operational amplifier are improved to achieve lower mismatch,and the mismatch of output voltage is less than 3m V within 1sigma.4.Based on the 0.18?m BCD process,the CMOS bandgap references are designed,simulated and layouted with the Cadence platform and Spectre tools.