模数转换器

In order to tackle the power hungry problem of most existing analog-to-digital converter, the power optimization aim at data converters was put forward.

为了解决目前音频应用模数转换器功耗过大的问题，提出了模数转换器低功耗设计的目标。

Equipped with AT89C51,the temperature sensor and the modulus convertor and coordinated by soft and hard wares,the system can fufil the instantaneous gathering of multichannel temperature signal,then,by meaus of asynchronous string communication,send the digital signal to PC which can separately display the instantaneous value and the average value of each channel temperature in bar diagram and weblike form,and print the temperature curve graph through data scale transferring,analyzing,and collating.

该系统运用单片机AT89C51、温度传感器保温器及模数转换器，通过软硬件的配合，实现了多路温度信号的实时采集，用异步串行通信发送数字信号到PC机，PC机经过数据的标度转换、分析、整理，分别用棒状图和网状表格显示各路温度瞬时值和平均值，打印出静态降温调温曲线图。

In the data acquisition system, CD4051 and AD574- the A/D transform, are used as hard core to receive the signal from the infra-red ray temperature sensor; the data acquisition depend on CPU; in the keyboard/ display system, a 74LS48 as the driver to drive LED works; in the warning circuit, I used two color LED and a buzzer as one unit to work; DAC0832 converter is the center of the D/A transform; execution unit, I used DDZIII type electromotive unit; the auto-man, it is a disabling of the other control circuit, this can secure production all the time.

在数据采集部分，以多路开关CD4051和AD574模/数转换器为核心接收来自红外线传感器的信号；数据处理依赖CPU；键盘/显示部分，以74LS48驱动LED数码管工作；报警单元，采用了双色LED加蜂鸣器的组合；D/A转换采用了DAC0832转换器；执行器采用DDZIII型电动执行器；手/自动切换装置则屏蔽了之前的电器部分，安全可靠。

It can complete the measurement of AC/DC voltage.The running process: it enlarges the digital to tallies chip through Amplifier. It holds the sampling digitalpass to convenience transforming for the chip through sample and hold Circuit.

运行过程是：将采样的模拟量通过放大电路放大到和模数转换芯片相适应的量，通过采样保持电路将芯片采样的量保持住后送入模数转换器转换成数字量，再由单片机进行控制计算。

It can complete the measurement of AC/DC voltage. The running process: it enlarges the digital to tallies chip through Amplifier. It holds the sampling digital pass to convenience transforming for the chip through sample and hold Circuit.

运行过程是：将采样的模拟量通过放大电路放大到和模数转换芯片相适应的量，通过采样保持电路将芯片采样的量保持住后送入模数转换器转换成数字量，再由单片机进行控制计算。

The ADC is pipelined, including a single-input/difference-output sample/hold circuit and nine stage subcircuits. The preceding eight stages are 1.5bits/stage, and the last stage consists of two comparators. Every input sample is converted into 18 bits binary signals, and these binary signals are converted into 10 bits binary signals through digital correction circuit.

模数转换电路采用流水线式的结构，包括具有单端输入/差动输出功能的采样保持电路和九级的子电路，前八级子电路使用1.5位/级的结构，最后一级使用两个比较器实现，每个输入值被转换为18位的二进制代码，通过数字纠正技术最终实现10位的输出，按照前端电路的应用要求，这个模数转换器实现1.33MHz的采样速率。

Analogtodigital converter is very important in digital signal process board,so calculation of the effective numbers of bits is of great importance for evaluation of system performance.

将模拟信号转换为数字信号后再进行处理，是当前信号处理普遍使用的方法，模数转换器就是将模拟信号转换为数字信号的器件，所以计算其有效转换位数对系统性能评估就显得尤为重要。

The data traffic is accomplished through the SCM and RS232 serial communication interface;the LCD1602 screen is used to display the pH value in real time. The C language is adopted to prepare control procedure in the software design,and the Visual C++ software is used to prepare the computer monitoring interface,so that the teledata monitoring can be finished easily.

硬件设计以AT89S52单片机为控制核心；传感器采用pH复合电极；为了与传感器的高内阻匹配，信号调理采用CA3140、UA741等运放构成三级放大电路；利用ADC0809模数转换器实现A/D转换；通过单片机与RS232串行通信口完成数据通信；使用1602液晶器实时显示pH值。

Sources of error in pipelined ADC and accuracy requirements of pipeline stage have been discussed in this thesis.

基于CMOS图像传感器中芯片级模数转换器高速、低功耗的要求，本文剖析和比较了三种典型高速模数转换器功耗，以确定选取流水线模数转换器。

This paper is finished based upon a part of the project ,which is the design of Delta-Sigma ADC in a high precision electrical meter chip .

本论文主要基于&一种高精度脉冲输出的电能计量集成电路&项目中关于Delta-Sigma模数转换器的设计部分，论文中在对Delta-Sigma模数转换器原理进行深入理解的基础上，提出了一种高精度Delta-Sigma模数转换器的解决方案，并运用于以上项目中取得很好的效果。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。