Research And Design Of High Speed SAR ADC

With the rapid development of terminal wireless communication,handheld medical imaging and handheld measuring instruments in recent years,the performance of high speed,high precision and low power consumption Analog-to-Digital Converter(ADC)are increasingly demanded.Among the all configurations of ADC,Successive-Approximation Register(SAR)ADC are suitable for designs with low power consumption because they have highly digitized structure and no static current.However,the overall conversion speed and accuracy of conventional SAR ADC are limited due to successive comparison and capacitance mismatch.In this thesis,a Pipelined-SAR ADC with high precision,high speed and low power is proposed,which effectively combines the low power characteristics of SAR sub-ADC and the high precision characteristics of Pipelined architecture.The 6bit and 9bit two-stage architecture,through the Pipeline,effectively increased the speed to 100MS/s.In the design process,through careful modeling analysis of Simulink,confirm the capacitor array capacitance size,k T/C noise,DC gain,bandwidth,establishment accuracy,interstage redundancy range and other parameters.The gm/I_Ddesign method is used to optimize the energy efficiency,noise and bandwidth of the residual amplifier,its equivalent input noise is 19.3μVrms and the unit-gain bandwidth is 2.47GHz,and the use of gain-boosting technology effectively increased its DC gain to 103d B.The comparator offset self-cancel technique avoids the loss in the speed of traditional auto-zero comparators and achieves a small comparison delay of 78ps.After calibration,the comparator’s equivalent input offset voltage 3 sigma value is 521μV.Finally,a pipeline-SAR ADC with 14bit resolution and 100MS/s sampling rate was designed under the standard 65nm CMOS technology,and the transistor level simulation and verification were completed.With a full amplitude sinusoidal input of 2.5MHz,the ADC achieves74d B Signal-to-noise-and-distortion ratio(signal-to-noise-and-distortion ratio,SNDR)and Spurious-Free Dynamic Range(SFDR)of 80d B,with power consumption of79.2m W and Schereir Fo M of 163.6d B.