模数转换系统通道间相互影响的原因及消除方法

数字式继电保护装置的模数转换系统多采用无源低通滤波＋多路模拟开关＋A／D转换器体系，在应用中发现当相邻两个通道的前一个通道输入量幅值远大于后一个通道时，后一个通道的转换结果相对误差很大，根据试验和理论分析，这种现象是由多路模拟开关输出引脚上的分布电容引起的，针对该问题，提出了一种电子开关将分布电容放电的方法，在成本增加不多的情况下可以将相对误差降低到可接受的水平以下。     

8通道24位模数转换器ADS1216原理及应用

本文从内部结构、外部引脚及内部工作寄存器三个方面对8通道24位模数转换器ADS1216进行了介绍．并以海洋光学浮标光学辐照度仪为例，介绍了它的应用。最后给出了ADS1216的一些使用要点及作者的一些设计经验。     

基于DSPs的同步采样系统及其在电力监控中的应用

设计了一种基于MAX125A／D转换芯片和TMS320F206数字信号处理器的采样系统，可以实现对三相电压和电流的同时采样，不但提高了采样速度，而且消除了电压和电流相位差的测量误差；提出了一种利用硬件测频电路计算频率偏差的方法，此方法使得在谐波分析时简化了各次谐波幅值和相角的修正计算。本采样电路已经应用于电力系统的FTU(馈线自动化终端单元)中。     

Compressive sampling-based strategy for enhancing ADCs resolution

The paper deals with the problem of simultaneously enhancing both horizontal and vertical resolution of analog-to-digital converters, with specific regard to low-cost conversion systems. To this aim, the authors propose the combined exploitation of a suitable Compressive Sampling (CS) approach and a proper digital signal processing stage. In particular, starting from a reduced number of digitized samples, the proposed CS-based sampling approach allows to recover an oversampled version of the input signal, whose spectral content is properly shaped to reject the most of in-band noise. The successive processing stage, implementing a low-pass filter, is mandated to drastically attenuate out-of-band noise components.Tests carried out on an actual microcontroller (namely, PIC32MX360L512 by Microchip) evidence the promising performance of the proposed sampling strategy. Results obtained either on single tone or multisine signals highlight a gain up to 3.5 bits in vertical resolution, while the sample rate increases 50 times with respect to the actual one adopted to randomly sample the input signal of interest.     

A low-power cryogenic analog to digital converter in standard CMOS technology

This paper presents a cryogenic successive approximation register (SAR) based analog to digital converter (ADC) in standard 0.35 μm complementary metal oxide semiconductor (CMOS) technology that functions from 300 K (room temperature) down to 20 K. It has been designed to operate in low temperature mid- and far-infrared imaging systems. In order to ensure the circuit performance at the extreme temperatures, a dedicated integral-based comparator architecture is employed. SPICE models have been developed for circuit simulation at 20 K. At 20 K, the experimental results exhibit that the ADC achieves 1.6 LSB maximum differential nonlinearity (DNL), 1.7 LSB maximum integral nonlinearity (INL), and 10.4 effective number of bits (ENOB) at 100 kS/s sampling rate with a current consumption of 75 μA from a 3.3 V supply.     

The influence of hydrogen production on the formation of metabolic pathways and regulation of ΔpH in Escherichia coli

Hydrogen (H₂) metabolism in Escherichia coli occurs via reversible membrane-associated hydrogenase enzymes (Hyd). Hyd-3 and Hyd-4 with formate dehydrogenase H (FDH-H) form formate hydrogen lyase complexes. The changes of metabolic pathways and ΔpH (pH_in-pH_ex) regulation during fermentation of glucose, glycerol and formate in non H₂-producing hypF (lack of all Hyds) and fdhF (lack of FDH-H) mutants at pH 7.5 were investigated. It was shown that specific growth rate was higher by ～23% in hypF and fdhF, compared to wild type (wt), suggesting the negative effect of H₂ on bacterial growth. Moreover, it was shown that H₂ generation did not have a vital role in glucose and glycerol utilization rate at 0–72 h. The utilization of external formate was detected in wt (～2.6 mM) and hypF (～0.68 mM), but not in fdhF, due to the absence of enzyme responsible for formate metabolism. Nevertheless, the changes in ΔpH were not evident at 3 h. The ratio of generated end-products and regulation of ΔpH at late log (6 h) and exponential phase (24, 72 h) were various in hypF and fdhF due to formate disproportionation in hypF and proton generation, therewith absence of H₂ generation. Taken together it can be concluded that bacteria regulate generation of fermentation end-products via balancing the concentration of acids and ethanol to maintain ΔpH and redox potential values. The results obtained are important for development and regulation of H₂ production technology when applying mixed carbon sources.     

一种应用于10 MHz 8位SAR ADC的分段式DAC电路设计

为了实现8位高性能的SAR ADC,设计了一种应用于8位SAR ADC的分段式结构DAC电路。采用二进制电容阵列,减小电容取值范围,有效提高精度,同时加快电容充放电速度,有效降低功耗,减小面积和成本。采用SMIC 65 nm CMOS工艺,工作于1.2 V电源电压,10 MHz采样频率,使用Cadence公司Spectre系列软件对设计的电路进行仿真。仿真结果显示,该分段式DAC电路可以有效实现8位数模转换,已成功应用于8位SAR ADC。     

一种复合型发泡剂ADC产品的研制

介绍一种有机固体为活化剂生产复合型发泡剂ADC产品方法,分析了复合型发泡剂ADC产品的生产技术,产品的发气量及分解温度与产品中活化剂成份比例关系等因素。     

Characterization of drying behavior of granular materials using magnetoelastic sensors

The aim of the present paper is to show that magnetoelastic sensors can furnish important information about the drying behavior of ceramic materials, and are, therefore, possible alternatives to ultrasonic or cantilever techniques. Sensitive measurements of the resonant frequency of coated amorphous ribbons show characteristic structures at different phases of drying. A model relating the resonant frequency of a magnetoelastic sensor to elastic properties of an applied thin film coating is extended to include the magnetic field dependence of the elastic modulus, the ΔE effect. In this manner, the stress developed during the drying process which contributes to the magnetic anisotropy, can be introduced into the problem. The model is applied to hard clay slurries drying on Metglas 2826MB3 ribbons. The long time value of the sensor resonant frequency is found to be consistent with elastic properties of the clay and the sensor appropriately indicates the appearance of stresses when the meniscus of the drying fluid begins to enter the pores of the solid.     

一款应用于多通道CZT探测器的12-bit 1MS/s SAR-ADC芯片

本文提出了一种应用于多通道CZT探测器低功耗、小面积、抗辐照12位1MS/s逐次逼近模数转换器芯片。为了提高SAR-ADC的精度,提出了一种新型比较器,该比较器能够实现失调电压自校准功能。同时为了减少电荷分配DAC中电容失配的问题,提出了分散式电容阵列。通过电路级和版图级技术加固,提高该SAR-ADC芯片的抗辐照能力。原型芯片采用TSMC 0.35um 2P4M CMOS工艺。电源电压为3.3V和5V,采样率是1MS/s。该SAR-ADC芯片能够实现高达67.64dB的信纳比SINAD,然而仅消耗10mWz功耗。该芯片核心面积为1180um×1080um。