Design Of Low Power Current Mode 12 Bits SAR ADC For Temperature Control

Compared to the voltage mode,the current mode circuits in the extended frequency band,simplify the circuit,to reduce the power consumption has a huge advantage,but is limited by the CMOS technology,a lot of theory of current mode circuits to stay on the stage,along with complementary bipolar technology,complementary metal-oxide technology and gallium arsenide technology mature,many of the early theory of current mode circuits are realized.The research of analog-to-digital converter using current mode is also receiving more and more attention.In this dissertation,a high precision and low power current-mode analog-to-digital converter for temperature control is designed based on 0.13μm Bi CMOS technology.It is used in the feedback regulating circuit of the microloop modulator to adjust the microloop modulator to work at the optimal temperature.It can directly convert the input current signal into 12-bit digital signal without the need of additional current-to-voltage module.The core circuit of the analog-to-digital converter includes current comparator,current-steering digital-to-analog converter,bandgap reference current source and clock logic circuit.The hybrid decoding method of the current-steering digital-to-analog converter can effectively reduce the dynamic performance degradation caused by competition and risk in the process of digital signal flipping and reduce the mismatch of current source array.The bandgap reference current source compensating for the reference current was used as the second-order reference,and the temperature coefficient of the reference current was reduced to 6.5 PPM/℃.The effect of temperature on the analog-to-digital converter is effectively reduced.The layout size of the 12-bit current mode SAR ADC designed in this paper is0.52mm×0.38 mm.The post-simulation results show that the maximum input current can reach3.4m A,the conversion rate can reach 79 k Hz,DNL and INL are less than 0.5 LSB,ENOB is more than 11 bits,SFDR is more than 70 d B,and the power consumption is less than 30 m W.The post-simulation results of each indicator meet the original design objectives,and the margin is sufficient,and the performance is good.