系统设计与误差分析，将测试线路及测试仪内部的线路电阻考虑在内时，电阻值的测量范围要达到100毫欧姆；为了准确测量出机体电阻，分辨率要达到0.1毫欧姆。从理论上说采用24bit的A/D转换器，若输入量程为5V，则分辨率可达，LSB=5/(224-1)=0.29微伏，即1mA电流流过1毫欧姆电阻产生的1微伏电压降也能测量出来。但这省略了一个前提：被测量信号的信噪比必须非常高。如果线路的噪声达到1mV，FFB0624EHE那么即使1A电流在1毫欧姆电阻上产生的1mV电压信号也检测不出来。台达风扇代理销售询购产品，欢迎咨询！根据需要测量的电阻值范围和对被测量信号信噪比的要求，设计的系统原理结构如图1所示。测试系统原理图，测试系统的误差分为量化误差Δd和模拟误差Δm两部分。可表示为，Δd=A/D转换器的积分非线性误差INL+A/D转换器的微分非线性误差DNL+量化误差LSB，Δm=被测量的电阻*比例误差系数+系统常数误差十随机误差。场效应晶体管放大器，场效应晶体管具有较高输入阻抗和低噪声等优点，因而也被广泛应用于各种电子设备中。尤其用场效管做整个电子设备的输入级，可以获得一般晶体管很难达到的性能。场效应管分成结型和绝缘栅型两大类，其控制原理都是一样的。如图1-1-1是两种型号的，表示符号，场效应管与晶体管的比较，场效应管是电压控制元件，而晶体管是电流控制元件。在只允许从信号源取较少电流的情况下，FFB0624EHE应选用场效应管；而在信号电压较低，又允许从信号源取较多电流的条件下，应选用晶体管。场效应管是利用多数载流子导电，所以称之为单极型器件，而晶体管是即有多数载流子，也利用少数载流子导电。被称之为双极型器件。有些场效应管的源极和漏极可以互换使用，栅压也可正可负，灵活性比晶体管好。afb0605lbafb0612lbafb0624lbafb0605mbafb0612mbafb0624mbafb0605hbafb0612hbafb0624hbafb0605hhbafb0612hhbAFB0624HHBAFB0612VHBAFB0624VHBAFB0605LDAFB0612LDAFB0624LDAFB0605MDAFB0612MDAFB0624MDAFB0605HDAFB0612HDAFB0612HDAFB0624HDAFB0605HHDAFB0612HHDAFB0624HHDAFB0612VHDAFB0624VHDAFB0612LAFB0624LAFB0612MAFB0624MAFB0612HAFB0624HAFB0612HHAFB0624HHAFB0648HHAFB0612VHAFB0624VHAFB0624VHAFB061248VHAFB0612SHAFB0624SHAFB0624SHAFB0648SHAFB0612EHAFB0624EHAFB0648EHAFB0705LAFB0712LAFB0724LAFB0748LAFB0705MAFB0712MAFB0724MAFB0748MAFB0705HAFB0712HAFB0724HAFB0748HAFB0712HHAFB0724HHAFB0748HHAFB0812LDAFB0824LDAFB0812MDAFB0824MDAFB0812HDAFB0824HDAFB0812HHDAFB0824HHDAFB0812VHDAFB0824VHDAFB0812SHDAFB0824VHDAFB0812SHDAFB0824SHDAFB0805LAFB0812LAFB0824LAFB0848LAFB0805MAFB0812MAFB0824MAFB0848MAFB0805HAFB0812HAFB0824HAFB0848HAFB0812HHAFB0824HHAFB0848HHAFB0812VHAFB0824VHAFB0812SHAFB0824SHAFB0912LAFB0924LAFB0912MAFB0924MAFB0948MAFB0912HAFB0948HAFB0912HHAFB0924HHAFB0948HHAFB0912VHAFB0924VHAFB1212LAFB1224LAFB1212MAFB1224MAFB1212HAFB1224HAFB1212HHAFB1224HHAFB1212VHAFB1224VHAFB1212SHAFB1224SHAFB1512LAFB1524LAFB1512MAFB1512HBFB0305LABFB0312LABFB0305MABFB0312MABFB0305HBBFB0312HABFB0305HHA)