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一、低噪声放大器设计的基本原理和方法在设计低噪声放大器时,信号源(传感器)的参数,如信号强度、内阻大小是已知的,同时还给定了信号传输指标和低噪声指标。怎样着手设计呢?根据经验,放大器的低噪声指标是最难达到的,着重放大器的低噪声指标进行设计,可以少走弯路,尽快设计出满足各项技术要求的放大器。放大器的噪声特性是用工作带宽上等效输入噪声电压来表示的。如图1所示多级放大器的噪声模型,不管有无反馈,系统等效到输入端的噪声电压都可表示为
A low noise amplifier design of the basic principles and methods In the design of low noise amplifier, the signal source (sensor) parameters, such as signal strength, resistance size is known, but also given the signal transmission and low noise indicators . How to proceed with the design? According to experience, the amplifier’s low noise figure is the most difficult to achieve, focusing on the design of the amplifier’s low noise index, you can detours, as soon as possible to design to meet the technical requirements of the amplifier. The noise characteristics of the amplifier are represented by the equivalent input noise voltage over the operating bandwidth. As shown in Figure 1 multi-stage amplifier noise model, with or without feedback, the system equivalent to the input voltage noise can be expressed as