The Design Of Balanced Low Noise Amplifier Based On WIMAX

In recent years, WIAMX has become the fourth communication standard of 3G mobile, following CDMA2000, WCDMA, TD-SCDMA. Compared to the other three communication standards, WIMAX owns obvious advantages in network coverage, bandwidth, etc, and so the study and analysis of the WIMAX is practically significant.As one of microwave receiving system modules, Low Noise Amplifier plays a decisive role on the entire system performance. The LNA is widely used in Microwave Communications, Radars, Electronic Countermeasures, Radio Astronomy, etc. Generally speaking, it’s necessary for LNA to meet basic performance index, which is a certain gain, low noise figure, high stability and adequate linearity.The article has introduced the basis theoretical of microwave LNA firstly, and then researched the design of the LNA which includes the choosing of biasing circuit, the design of the matching circuit and the improving method of the stability of LNA, etc. A LNA which has a frequency range of 3.3GHz to 3.7GHz were designed by using the microwave circuit simulation software Advanced Design System. In 3.3GHz to 3.7GHz frequency range, the balanced low noise amplifier’s simulation results show that the gain is more than 14dB, VSWR less than 1.2,the circuit stability is more than 1,and the noise figure is less than 1.2dB.The LNA is achieved according to the simulation, the test result of which is the gain more than 13dB, VSWR less than 1.5, the circuit stability more than 1,which has reached the aim of design.