| With the development and application of 5G communication technology,human-computer interaction has developed rapidly.Delta-Sigma ADC has the advantages of high precision,high linearity,and insensitivity to the non-ideal characteristics of the circuit,so it is more and more popular in various semiconductor sensors and microcomputer systems.In mobile devices,analog-to-digital converters applied to pressure sensors need to meet the characteristics of low power consumption.The power consumption of the circuit can be reduced by reducing the power supply voltage,but reducing the power consumption of the circuit will inevitably lead to a decrease in accuracy,the output voltage of a pressure sensor powered by 3.3V will be greater than 1.2V.If the delta-sigma ADC is designed with a 1.2V process to obtain low power consumption,the input voltage amplitude of the delta-sigma ADC will be less than 1.2V,the output signal of the pressure sensor cannot be converted from analog to digital.In order to solve this problem,this study uses delta-sigma ADC to have different working states,and in a certain state,some modules do not need features,so that the unnecessary circuit does not work to reduce the power consumption of Delta-sigma ADC.The main tasks are as follows:(1)The structural characteristics,basic principles and main performance indicators of delta-sigma ADC are studied.(2)According to the characteristics of the ADC in the pressure sensor,it is preliminarily determined that the structure adopted in this design is a second-order single-loop feedback type,and the Matlab and Simulink tools are used for modeling to verify the feasibility of the circuit structure and design parameters.(3)Under the Smic0.13μM 3.3V CMOS process,the design of the second-order single-loop feedback Delta-sigma ADC circuit is completed,including two-phase non-overlapping clocks,CMOS switches,operational amplifiers,switched capacitor integrators,and 1 Bit quantizer,1-bit feedback DAC,adder,common mode voltage generating circuit,variable temperature point current compensation band-gap reference voltage source and other modules.Cadence simulation verification results show that the overall power consumption of the ADC has dropped from 4.5m W to 1.76m W.In the case of 1.9V,2KHz sinusoidal signal input,16.3bit accuracy can be achieved.The temperature drift coefficient of the band-gap reference voltage source is1.68ppm/~oC,the post-imitation temperature drift result is 2.08ppm/~oC,and the power supply voltage rejection ratio is 90.4d B. |
