噪声系数测量--三种方法（Measurement of noise coefficient - three methods）.doc

噪声系数测量--三种方法（Measurement of noise coefficient - three methods） Three methods of measurement of noise coefficient Abstract: this paper introduces three methods of measuring noise coefficient: gain method, Y coefficient method and noise coefficient test method. The comparison of these three methods is given in the form. In the wireless communication system, the noise factor (NF) or corresponding noise factor (F) defines the noise performance and the contribution to the receiver sensitivity. This paper elaborates on this important parameter and its different measurement methods. Noise and noise coefficients Noise factor (NF) is also sometimes referred to as noise factor (F). The simple relationship is: NF = 10 * log10 (F) define Noise factor (noise factor) contains important information about noise performance of rf system. The standard definition is: From this definition, many common noise coefficients (noise factor) formulae can be derived. The following table is typical of rf noise coefficient: Category MAXIM Products Noise Figure * Applications Operating Frequency System Gain LNA MAX2640 0.9 dB Cellular, ISM 400MHz ~ 1500MHz 15.1 dB LNA MAX2645 HG: 2.3 dB WLL 3.4 GHz ~ 3.8 GHz HG: 14.4 dB LG: 15.5 dB WLL 3.4 GHz ~ 3.8ghz LG: -9.7 dB Mixer Max 2684 13.6 dB LMDS, WLL 3.4 GHz ~ 3.8ghz 1dB Mixer MAX9982 12dB Cellular, GSM 825MHz ~ 915MHz 2.0 dB Receiver System Max 2700 3.5 dB ~ 19dB PCS, WLL 1.8 GHz ~ 2.5ghz 80dB * HG = high gain mode, LG = low gain mode The measurement method of noise coefficient varies with the application. You can see from the table above, some applications with high gain and low noise factor (low noise amplifier (LNA) under the high gain mode), and others with low noise and high gain coefficient (mixer and LNA in low gain mode), some with very high gain and wide range of noise coefficient (receiver). So the measurement must be carefully chosen. In this article, we will discuss the noise coefficient test method and the other two methods: the gain m