Design And Implementation Of Broadband Low Noise Amplifier Based On SiGe HBT

Low noise amplifiers(LNAs)are an important module in wireless communication systems.Due to its special location in the receiving system,it has important application value for the research of LNA.Two LNAs are designed based on SiGe HBT in the frequency range 1.6-2.4GHz and 6-10GHz.First,the performance of the LNA are analyzed,including gain,noise,bandwidth,stability and standing wave ratio.The topo:logy of the low noise amplifier is summarized and compared.Secondly,the design of LNA in the 1.6-2.4GHz band was completed by using NXP s SiGe hetero-junction bipolar transistor.According to the design index,the output characteristics of the transistor are scanned and the optimal operating point is determined.The gain flatness of the LNA is improved by adding an RC network between the base and the collector of the transistor to compensate for the attenuated gain,and paralleling the RC circuit at its output port to reduce the low band gain.The noise figure and power gain of the low noise amplifier are mutually constrained.In this paper,the input impedance matching is completed by choosing the best source impedance point between the minimum noise and the maximum gain.In the LNA layout,a large area of copper is used as the ground line and the parallel capacitor at the power supply pin to bypasses the high frequency signal introduced from the outside.The test results show that the return loss of the LNA input and output ports are less than-10dB,the power gain is 15dBt0.5dB,the flatness is well and the noise figure is less than 1.8dB.Finally,the design of the 6-10GHz low noise amplifier was completed.For this low noise amplifier,a negative feedback and attenuation network are used to improve the gain flatness and stability of the LNA.The amplifier is composed of two SiGe HBT transistors combined with a direct coupling of capacitors.The result of the layout simulation shows that the LNA has a noise figure of less than 2.5dB,the power gain is between 20-22.5dB,the gain flatness is less than 2.5dB and the input and output return loss are less than-10dB.The results of the LNA simulation meet the design specifications.