为解决传统电平交叉模数转换器(LC ADC)精度较低和噪声整形逐次逼近寄存器(NS SAR)ADC功耗较大的问题,提出了一种应用于移动物联网(IoT)随机稀疏信号采集的LC-NS SAR ADC。在NS SAR ADC前端插入8 bit的LC ADC作为输入信号活跃度的预检...为解决传统电平交叉模数转换器(LC ADC)精度较低和噪声整形逐次逼近寄存器(NS SAR)ADC功耗较大的问题,提出了一种应用于移动物联网(IoT)随机稀疏信号采集的LC-NS SAR ADC。在NS SAR ADC前端插入8 bit的LC ADC作为输入信号活跃度的预检测电路,在电平交叉发生后开启NS SAR ADC的转换。二阶无源噪声整形电路积分过程只在事件触发后发生,从而能够根据输入信号的活跃度动态调节整体功耗。在1.8 V 180 nm CMOS工艺、采样率为40 kS/s、过采样率(OSR)为20、带宽为1 kHz下对该ADC进行仿真验证,结果表明信噪失真比(SNDR)达到87 dB,电路功耗为2.70μW,心电图信号输入时功耗仅为0.79μW,相较于传统等间隔奈奎斯特采样ADC,采样点减少了73%,在处理生物医学信号时实现了约5∶1的数据压缩比,Schreier品质因数(FoMs)和Walden品质因数(FoMw)分别为172.6 dB和67.0 fJ/conv.step。展开更多
This study investigates the air–water interaction dynamics in jet streams,with particular emphasis on the transition from the cavity to the far-field regions.A dual-tip conductivity phase-detection probe was employed...This study investigates the air–water interaction dynamics in jet streams,with particular emphasis on the transition from the cavity to the far-field regions.A dual-tip conductivity phase-detection probe was employed to analyze four distinct downstream water levels.Based on the development of the cross-sectional mean air concentration,the jet flow was divided into four distinct regions:the jet length region,impact region,splash region,and far-field region.The results demonstrate varying trends in the evolution of the mean air concentration and maximum bubble frequency.Downstream water levels exerted a significant influence on these parameters in the splash and far-field regions,whereas minimal variation was observed in the impact region.Additionally,notable differences were identified in the probability density function of water droplets between the cavity and downstream regions.Furthermore,downstream water depth was found to have a negligible effect on the proportion of small-sized droplets in both the impact and splash regions.展开更多
文摘为解决传统电平交叉模数转换器(LC ADC)精度较低和噪声整形逐次逼近寄存器(NS SAR)ADC功耗较大的问题,提出了一种应用于移动物联网(IoT)随机稀疏信号采集的LC-NS SAR ADC。在NS SAR ADC前端插入8 bit的LC ADC作为输入信号活跃度的预检测电路,在电平交叉发生后开启NS SAR ADC的转换。二阶无源噪声整形电路积分过程只在事件触发后发生,从而能够根据输入信号的活跃度动态调节整体功耗。在1.8 V 180 nm CMOS工艺、采样率为40 kS/s、过采样率(OSR)为20、带宽为1 kHz下对该ADC进行仿真验证,结果表明信噪失真比(SNDR)达到87 dB,电路功耗为2.70μW,心电图信号输入时功耗仅为0.79μW,相较于传统等间隔奈奎斯特采样ADC,采样点减少了73%,在处理生物医学信号时实现了约5∶1的数据压缩比,Schreier品质因数(FoMs)和Walden品质因数(FoMw)分别为172.6 dB和67.0 fJ/conv.step。
基金supported by the National Natural Science Foundation of China(52479068)Open Fund Research from the State Key Laboratory of Hydraulics and Mountain River Engineering(SKHL2323).
文摘This study investigates the air–water interaction dynamics in jet streams,with particular emphasis on the transition from the cavity to the far-field regions.A dual-tip conductivity phase-detection probe was employed to analyze four distinct downstream water levels.Based on the development of the cross-sectional mean air concentration,the jet flow was divided into four distinct regions:the jet length region,impact region,splash region,and far-field region.The results demonstrate varying trends in the evolution of the mean air concentration and maximum bubble frequency.Downstream water levels exerted a significant influence on these parameters in the splash and far-field regions,whereas minimal variation was observed in the impact region.Additionally,notable differences were identified in the probability density function of water droplets between the cavity and downstream regions.Furthermore,downstream water depth was found to have a negligible effect on the proportion of small-sized droplets in both the impact and splash regions.
