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信号检测系统中关键部件之一的低噪声前置放大器,通常是由低噪声放大器件及反馈网络联接而成.电路低噪声设计目的不仅是计算放大器的最佳源阻抗及最小噪声系数,而且要通过改变电路形式及反馈元件参数全面比较其性能,以期有好的噪声性能指标同时,能兼顾放大器其他性能指标.国内外现使用的噪声源迭加法是对电路中每个噪声源分别计算输出噪声功率,通过功率迭加法得到总输出噪声功率后,再等效到输入端的电压噪声E_n及电流噪声I_n,从而求出最小噪声系数及最佳源阻抗.由于电路中(特别是器件内部)有大量噪声源,这种方法的计算量十分惊人.而且由于噪声源之间相关性无法考虑,使计算误差较大(最多可
The low-noise preamplifier, one of the key components in the signal detection system, is usually a combination of a low-noise amplifier and a feedback network. The purpose of the low-noise circuit design is not only to calculate the optimal source impedance and minimum noise figure of the amplifier, By changing the circuit form and the parameters of the feedback components to fully compare their performance in the hope of having good noise performance indicators, while taking into account the other performance indicators of the amplifier.Non-current noise source superposition method is used to calculate the output noise for each noise source in the circuit Power, the total output noise power is obtained by superposition of power, and then equivalent to the input voltage noise E_n and current noise I_n, so as to find the minimum noise figure and the optimal source impedance.Because the circuit (especially within the device) a large number Noise sources, this method of calculation is very alarming. And because of the correlation between noise sources can not be considered, the calculation error is large (up to