The Rearch On Amplifier Circuit Of Multi-mode Navigation Receiver

In recent years, the development of satellite navigation system has been making a great progress. The application of navigation receiver becomes more and more widely in military, meteorological, oceanographic and transportation industries and so on. The accuracy and the coverage of single satellite positioning system are unable to meet system’s demand. Multi-mode navigation receiver has become the mainstream and it receives signals radiate by different satellites and selects the system flexibly. The low noise amplifier behind the antenna has a great influence on the sensitivity; the received signal is mixed with different bands in the multi-mode and multi-frequency receiver system. If the span of the amplifier is narrow, it needs to filter the signal for different amplifiers and that’s will make the circuit become more complex. Using a narrowband amplifier not only does not meet the characteristics of portable, but also deteriorate the performance of the receiver system. RF signal will lose some power in the process of transmitting and the power amplifier in the transmitter channel amplify low level signal to high power level, the design of the broadband power amplifier can reduce the complexity and cost of the receiver circuit. Therefore, the multimode and multi-frequency amplifier is very important to the development of multi-frequency receiver.In this paper, a broadband low noise amplifier and a broadband power amplifier were designed. The basic theories and indexes of low noise amplifier were introduced first, and then the PHEMT ATF-54143produced by Agilent was selected as the active element of the amplifying circuit. In order to meet the needs of multi-frequency receiver, the LNA was optimized by balanced amplifier through theoretical analysis. It indicated that the amplifier meet the design requirements in broadband and suitable for multimode navigation receiver through the testing and debugging. At the end of this paper, to meet the requirement of remote transmitter, a broadband power amplifier was simulated by ADS, the transistor is CGH40010provided by CREE and the output power of the amplifier was10W. In order to expand the bandwidth of the amplifier, using the sector micro strip instead of the open transmission line in the bias circuit. The simulation results show that the bandwidth of the amplifier was expanded and meet the needs of multimode navigation receiver.