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作为宽带低噪声放大器中的 GaAs 肖特基势垒栅场效应晶体管的设计基础,本文以半经验的方式研究了基本器件参数与两端噪声参数之间的关系。一组四个噪声参数表示为 GaAs 肖特基势垒栅场效应晶体管的等效电路元件的简单函数。然后,每个元件以这个器件的几何和材料参数的简单解析式表示。这样,依据几何和材料参数就建立起四个噪声参数的实用表达式。在这四个噪声参数中,对于宽带低噪声放大器来说最小噪声系数F_(min)和等效噪声电阻 R_n 是起决定性的。低的 R_n 对输入失配较不灵敏,且能够由一个短的重掺杂薄有源沟道获得。这样一个高沟道掺杂厚度比率(N/a)能产生高功率增益,但与得到低噪声系数 F_(min)是相矛盾的。所以,对于最好的全面的放大器性能来说,折衷选择掺杂浓度 N和沟道厚度 a 是必要的。为表示最佳选择给出了四个数字例子。
As a design basis for GaAs Schottky barrier field effect transistors in wideband LNAs, the relationship between basic device parameters and the noise parameters at both ends is studied semi-empirically. A set of four noise parameters represents a simple function of the equivalent circuit elements of a GaAs Schottky barrier field effect transistor. Then, each element is represented by a simple analytical expression of the geometry and material parameters of the device. Thus, a practical expression of four noise parameters is established based on geometry and material parameters. Among the four noise parameters, the minimum noise figure F min and the equivalent noise resistance R n are decisive for a broadband low-noise amplifier. Low R_n is less sensitive to input mismatch and can be obtained from a short heavily doped thin active channel. Such a high channel doping thickness ratio (N / a) produces a high power gain, but contradicts the low noise figure F min. So, for the best overall amplifier performance, it is necessary to compromise between doping concentration N and channel thickness a. Four numerical examples are given to show the best choice.