放大器测试

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对于正弦输入，输出包含基波的所有谐波。这门课有放大器增益的规则，我们将看到如何用一对晶体管来制作差分放大器;对于这些残差畸变是对称的，并且只包含奇谐波。我们将看到差动整流器中消除畸变的一些非常巧妙的方法。
发射极简并放大器本身使用一种形式的负反馈。把晶体管看作是一个跨导器件，根据基极和发射极之间施加的电压来确定集电极电流(从而确定输出电压);但是放大器的输入是基极到地的电压。所以从基极到发射极的电压是输入电压，减去输出的一个样本(即IERE)。这就是负反馈，这就是为什么发射极退化改善了放大器的大部分特性(这里改善了线性和稳定性，增加了输入阻抗)，当我们第一次看到反馈时，我们将对这些声明进行定量分析。随着放大器测试中反馈的全面提高，有很多值得期待的事情。
For sinusoidal input, the output contains all harmonics of the fundamental wave. rules of amplifier gain are available to the subject, and we’ll see how to make differential amplifiers with a pair of transistors; for these the residual distortion is symmetric, and contains only the odd harmonics. we’ll see some very clever methods for cancelling distortion in differential rectifier.
the emitter-degenerated amplifier itself uses a form of negative feedback. Think of the transistor as a transconductance device, determining collector current (and therefore output voltage) according to the voltage applied between the base and emitter; but the input to the amplifier is the voltage from base to ground. So the voltage from base to emitter is the input voltage, minus a sample of the output (namely IERE). That’s negative feedback, and that’s why emitter degeneration improves most properties of the amplifier (here improved linearity and stability and increased input impedance) we’ll make these statements quantitative when we first look at feedback. And there are great things to look forward to, with the full fowering of feedback in amplifier test.