浅析adc的六种分类以及六大关键性能指标

shuszhao

<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">过采样频率:增加一位分辨率或每减小6dB 的噪声，需要以4 倍的采样频率fs 进行过采样.假设一个系统使用12 位的ADC，每秒输出一个温度值(1Hz)，为了将测量分辨率增加到16 位，按下式计算过采样频率： fos=4^4*1(Hz)=256(Hz)。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">1. AD转换器的分类<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">下面简要介绍常用的几种类型的基本原理及特点：积分型、逐次逼近型、并行比较型/串并行型、Σ-Δ调制型、电容阵列逐次比较型及压频变换型。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">1)积分型<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">积分型AD工作原理是将输入电压转换成时间(脉冲宽度信号)或频率(脉冲频率)，然后由定时器/计数器获得数字值。其优点是用简单电路就能获得高分辨率，抗干扰能力强(为何抗干扰性强?原因假设一个对于零点正负的白噪声干扰，显然一积分，则会滤掉该噪声)，但缺点是由于转换精度依赖于积分时间，因此转换速率极低。初期的单片AD转换器大多采用积分型，现在逐次比较型已逐步成为主流。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">2)逐次比较型SAR<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">逐次比较型AD由一个比较器和DA转换器通过逐次比较逻辑构成，从MSB开始，顺序地对每一位将输入电压与内置DA转换器输出进行比较，经n次比较而输出数字值。其电路规模属于中等。其优点是速度较高、功耗低，在低分辩率(<12位)时价格便宜，但高精度(>12位)时价格很高。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">3)并行比较型/串并行比较型<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">并行比较型AD采用多个比较器，仅作一次比较而实行转换，又称FLash(快速)型。由于转换速率极高，n位的转换需要2n-1个比较器，因此电路规模也极大，价格也高，只适用于视频AD转换器等速度特别高的领域。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">串并行比较型AD结构上介于并行型和逐次比较型之间，最典型的是由2个n/2位的并行型AD转换器配合DA转换器组成，用两次比较实行转换，所以称为 Half flash(半快速)型。还有分成三步或多步实现AD转换的叫做分级(Multistep/Subrangling)型AD，而从转换时序角度又可称为流水线(Pipelined)型AD，现代的分级型AD中还加入了对多次转换结果作数字运算而修正特性等功能。这类AD速度比逐次比较型高，电路 规模比并行型小。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">4)Σ-Δ(Sigma delta)调制型(如AD7705)<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">Σ-Δ型AD由积分器、比较器、1位DA转换器和数字滤波器等组成。原理上近似于积分型，将输入电压转换成时间(脉冲宽度)信号，用数字滤波器处理后得到数字值。电路的数字部分基本上容易单片化，因此容易做到高分辨率。主要用于音频和测量。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">5)电容阵列逐次比较型<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">电容阵列逐次比较型AD在内置DA转换器中采用电容矩阵方式，也可称为电荷再分配型。一般的电阻阵列DA转换器中多数电阻的值必须一致，在单芯片上生成高 精度的电阻并不容易。如果用电容阵列取代电阻阵列，可以用低廉成本制成高精度单片AD转换器。最近的逐次比较型AD转换器大多为电容阵列式的。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">6)压频变换型(如AD650)
压频变换型(Voltage-Frequency Converter)是通过间接转换方式实现模数转换的。其原理是首先将输入的模拟信号转换成频率，然 后用计数器将频率转换成数字量。从理论上讲这种AD的分辨率几乎可以无限增加，只要采样的时间能够满足输出频率分辨率要求的累积脉冲个数的宽度。其优点是分辩率高、功耗低、价格低，但是需要外部计数电路共同完成AD转换。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">2. AD转换器的主要技术指标<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">1)分辩率(Resolution) 指数字量变化一个最小量时模拟信号的变化量，定义为满刻度与2n的比值。分辩率又称精度，通常以数字信号的位数来表示。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">2).转换速率(Conversion Rate)是指完成一次从模拟转换到数字的AD转换所需的时间的倒数。积分型AD的转换时间是毫秒级属低速AD，逐次比 较型AD是微秒级属中速AD，全并行/串并行型AD可达到纳秒级。采样时间则是另外一个概念，是指两次转换的间隔。为了保证转换的正确完成，采样速率 (Sample Rate)必须小于或等于转换速率。因此有人习惯上将转换速率在数值上等同于采样速率也是可以接受的。常用单位是ksps和Msps，表示每秒采样千/百万次(kilo / Million Samples per Second)。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">3)量化误差(Quantizing Error)
由于AD的有限分辩率而引起的误差，即有限分辩率AD的阶梯状转移特性曲线与无限分辩率AD(理想AD)的转移特 性曲线(直线)之间的最大偏差。通常是1 个或半个最小数字量的模拟变化量，表示为1LSB、1/2LSB。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">4)偏移误差(Offset Error) 输入信号为零时输出信号不为零的值，可外接电位器调至最小。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">5)满刻度误差(Full Scale Error) 满度输出时对应的输入信号与理想输入信号值之差。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">6)线性度(Linearity) 实际转换器的转移函数与理想直线的最大偏移，不包括以上三种误差。 INL 和DNL区别说精度之前，首先要说分辨率。最近已经有贴子热门讨论了这个问题，结论是分辨率决不等同于精度。比如一块精度0.2%(或常说的准确度0.2级)的四位半万用表，测得A点电压1.0000V，B电压1.0005V,可以分辨出B比A高0.0005V，但A点电压的真实值可能在0.9980~1.0020之间不确定。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">那么,既然数字万用表存在着精度和分辨率两个指标，那么,对于ADC和DAC，除了分辨率以外，也存在精度的指标。 模数器件的精度指标是用积分非线性度(Interger NonLiner)即INL值来表示。也有的器件手册用 Linearity error 来表示。INL表示了ADC器件在所有的数值点上对应的模拟值，和真实值之间误差最大的那一点的误差值。也就是，输出数值偏离线性最大的距离。单位是LSB(即最低位所表示的量)。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">下面再说DNL值<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">理论上说，模数器件相邻量个数据之间，模拟量的差值都是一样的。就相一把疏密均匀的尺子。但实际并不如此。一把分辨率1毫米的尺子，相邻两刻度之间也不可能都是1毫米整。那么，ADC相邻两刻度之间最大的差异就叫差分非线性值(Differencial NonLiner)。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">DNL值如果大于1，那么这个ADC甚至不能保证是单调的，输入电压增大，在某个点数值反而会减小。这种现象在SAR(逐位比较)型ADC中很常见。 很多分辨率相同的ADC，价格却相差很多。除了速度、温度等级等原因之外，就是INL、DNL这两个值的差异了。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">另外，工艺和原理也决定了精度。比如SAR型ADC，由于采用了R-2R或C-2C型结构，使得高权值电阻的一点点误差，将造成末位好几位的误差。在SAR型ADC的2^n点附近，比如128、1024、2048、切换权值点阻，误差是最大的。1024值对应的电压甚至可能会比1023值对应电压要小。这就是很多SAR型器件DNL值会超过1的原因。但SAR型ADC的INL值都很小，因为权值电阻的误差不会累加。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">和SAR型器件完全相反的是阶梯电阻型模数/数模器件。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">这里要提一下双积分ADC，它的原理就能保证线性。 还要特别提一下基准源。基准源是测量精度的重要保证。基准的关键指标是温飘，一般用ppm/K(ppm百万分之一)来表示。假设某基准30ppm/K，系统在20~70度之间工作，温度跨度50度，那么，会引起基准电压30*50=1500ppm的漂移，从而带来0.15%的误差。温漂越小的基准源越贵。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">说起来好笑的一个现象：我这边新来的学生大多第一次设计ADC电路的时候，基准直接连VCC，还理直气壮的找来N本教科书，书上的基准写了个网标：+5V。<div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255); min-height: 8pt;"> <div style='margin: 0px 0px 10px; padding: 0px; text-align: justify; color: rgb(100, 100, 100); text-transform: none; text-indent: 0px; letter-spacing: normal; font-family: myFont, "Microsoft YaHei"; font-size: 16px; font-style: normal; font-weight: normal; word-spacing: 0px; white-space: normal; word-wrap: break-word; box-sizing: border-box; orphans: 2; widows: 2; background-color: rgb(255, 255, 255); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;' .="margin: 0px; padding: 0px; border: 0px; font-size: 15px; font-family: "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; vertical-align: baseline; word-wrap: break-word; background-color: rgb(255, 255, 255);">天下的书互相抄，也就所有的学校的教科书都是基准接5V。教科书把5V改成5.000V多好？学生就会知道，这个5V不是VCC。或者提一下基准需要高稳定度也好啊！

sun5304

    

amu0809

这个格式看不懂啊