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理想放大器满足下列条件： |
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开环差模电压增益
Aod→∞；
开环输出电阻ro→0；
共模电压放大倍数Aoc→0；
失调电压和失调电流UIo＝0，IIo＝0；
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开环差模输入电阻rid→∞；
输入偏置电流IIB1=IIB2=0；
单位增益带宽，fc→∞。
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理想放大器两个重要特点： |
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IIB1=IIB2=0,
rid→∞；流入放大器反相输入端和同相输入端的电流I-，
I+均等于零。I-＝ I+＝０
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9.1.1 运算电路 |
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一、比例电路 |
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(一)反相比例电路 |
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Uo=-(Rf/Ri)Ui |
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电路完成了对输入信号的反相比例运算，故称为反相比例电路。Rf
= R1，则输出电压与输入电压相位相反，大小相等，称为反相器。 |
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(二)同相比例电路 |
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Uo=Ui(1+Rf/Ri) |
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电路的输出电压与输入电压相位相同，大小成一定比例关系，但一定大于或等于1。电路完成了对输入信号的同相比例运算 |
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当Rf＝0或R1＝∞，Af＝1，即输出电压与输入电压大小相等相位相同。 |
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①
输入电阻很高，可高达1000MΩ以上。
② U+＝U-＝UI
,共模输入信号高为UI
,对集成运放共模抑制比要求高。
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