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一、引言对数放大器由于其输出是输入的对数函数,因而它具有把大输入动态范围压缩成小输出动态范围的独特性能。这种性能对于许多电量的测量是非常有用的,因为许多电量的测量必须在很宽的输入动态范围内进行,它们的输入信号往往从几微伏到几伏。一般的线性放大器由于下限受所要求的信噪比的限制而上限受饱和或限幅电平的限制,其可用的瞬时输入动态范围通常小于30dB,这对于许多应用来说是
I. INTRODUCTION Logarithmic amplifier has the unique performance of compressing large input dynamic range into small output dynamic range because its output is a logarithmic input. This performance is very useful for many power measurements because many measurements must be made over a wide range of input dynamic and their input signal tends to be from a few microvolts to a few volts. A typical linear amplifier with its lower limit being limited by the required signal-to-noise ratio and limited by saturation or clipping levels has a usable transient input dynamic range of typically less than 30 dB, which for many applications is