实验十 集成运算放大器的应用(二)
信号处理─电压比较器
预习部分
一、实验目的
1. 掌握比较器的电路构成及特点
2. 学会测试比较器的方法
二、实验原理
1. 信号幅度比较就是将一个模拟量的电压信号去和一个参考电压相比较,在二者幅度相等的附近,输出电压将产生跃变。通常用于越限报警,模数转换和波形变换等场合。此时,幅度鉴别的精确性、稳定性以及输出反应的快速性是主要的技术指标。
图2-10-1所示为一最简单的电压比较器,UR为参考电压,加在运放的同相输入端,输入电压ui加在反相输入端。
当ui<UR时,运放输出高电平,UO¢=UOM,若输出端采用双向稳压管限幅(RO为限流电阻),输出UO被箝位在稳压管的稳定电压Uz,即:Uo=Uz
当ui>UR时,运放输出低电平,UO¢= -UOM ,若输出端采用双向稳压管限幅,输出UO被箝位在稳压管的稳定电压Uz,即:Uo= -Uz 。
因此,以UR为界,当输入电压ui变化时,输出端反映出两种状态:高电位和低电位,ui=UR即为输出状态转换的临界点。当UR =0时,比较器为过零比较器。
表示输出电压与输入电压之间关系的特性曲线, 称为传输特性。 图2-10-1(b)为(a)图比较器的传输特性。
(a) 电路图 (b) 传输特性
图2-10-1 电压比较器
2. 具有滞回特性的电平检测器(施密特触发器)。
比较器在实际工作时,如果ui恰好在等于UR值附近,则由于零点漂移的存在,uo将不断由一个极限值转换到另一个极限值,这在控制系统中,对执行机构将是很不利的。为此, 就需要输出特性具有滞回现象。具有滞回特性的电平检测器按其电路结构或传输特性的不同,可分为两类:滞回特性反相电平检测器(如图2-10-2所示)和滞回特性同相电平检测器(如图2-10-3所示)。
1) 图2-10-2为具有滞回特性的反相电平检测器,不难得出:
2) 图2-10-3为具有滞回特性的同相电平检测器,同理,由叠加原理得出:
三、预习要求
1. 复习教材有关比较器的内容。
2. 画出各类比较器的传输特性曲线。
3.试推导具有滞回特性的同相输入电平检测器的U1,U2,UH公式,讨论当R2=mR1,Rf=nR1时电路的特点。
实验部分
一、实验设备与器件
二、实验内容
1.电压比较器,实验电路如图2-10-1所示
(1) 接通±12V电源。
(2) 参考电压UR为不同值时,ui接可调直流电源,改变ui幅值,测量Uo电压,测量传输特性曲线。(ui幅值自行选定,在接近临界值附近可多测几点)
(3) ui输入500Hz、幅值为2V的正弦信号,观察ui--uo的波形(在同一坐标下)并记录。
表2-10-1
2. 具有滞回特性的反相电平检测器,实验电路如图2-10-2所示。
(1)按图接线,UR=0,ui接可调直流电源,①测出uo由+Uz→-Uz时ui的临界值U1。②测出uo由-Uz→+Uz时ui的临界值U2。③ui接500Hz,峰值为2V的正弦信号,观察并记录 ui─uo波形。
(2)将分压支路电阻RF由100K改为200K,重复步骤(1)。
(3)UR=1V,重复步骤(1)。
表2-10-2
3.* 具有滞回特性的同相电平检测器,实验电路如图2-10-3所示。
(1)按图接线,UR=0,ui接可调直流电源,①测出uo由+Uz→-Uz时ui的临界值U2。②测出uo由-Uz→+Uz时ui的临界值U1。③ui接500Hz,峰值为2V的正弦信号,观察并记录 ui─uo波形。
(2)UR=1V,重复步骤(1)。
(3)将分压支路电阻R2由10K改为20K, RF=100K,重复步骤(1)。
(4)将分压支路电阻RF由100K改为200K,R2=10K,重复步骤(1)。
表2-10-3
三、实验报告
1. 整理实验数据,绘制各类比较器的传输特性曲线
2. 总结几种比较器的特点,阐明它们的应用。
第二篇:集成运算放大器比较器SA58603
Philips SemiconductorsProduct dataHigh precision operational amplifier,
comparator, and voltage referenceSA58603SO8:plastic small outline package; 8 leads; body width 3.9 mm
pin 1 index
B2
1.734.950.514.951.27
4.800.334.800.380.076
0.0680.1890.0130.050
0.1950.0200.0150.003
SO8
2001 Oct 038
Philips SemiconductorsProduct dataHigh precision operational amplifier,
comparator, and voltage referenceSA58603
NOTES
2001 Oct 039
Philips SemiconductorsProduct dataHigh precision operational amplifier,
comparator, and voltage reference
SA58603DefinitionsShort-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. Fordetailed information see the relevant data sheet or data handbook.Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 60134). Stress above oneor more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these orat any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extendedperiods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. PhilipsSemiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing ormodification.
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