The Research And Design Of The RF Front System Of The Beidou RDSS/RNSS Dual Mode Receiver

With the rapid development of electronic information,the industry of satellite navigation has become a hot industry of informational communication following the mobile communication and Internet.The satellite navigation and positioning system of Beidou,which is developed and put into operation by our country independently,has a wide range of application fields because it can combined navigation with informational communication.With the Beidou satellite navigation system becoming mature progressively,the performance of the RF front receiver,which is one of the key technics of Beidou satellite navigation terminals,affects the sensitivity and accuracy of the whole receiver.Therefore,the research and design of high performance of the RF front system of the Beidou is of great significance and value.Currently,the active positioning system(RDSS)and the passive positioning system(RNSS)of navigation system of Beidou are running at the same time.So this thesis researches and designs for the Beidou dual mode RF front system,and the main content is divided into two parts.Firstly,it analyses the RF front system of dual mode receiver and simulates the performance of the central circuit,which is named low noise amplifier.Secondly,it uses the computer-aided designed tools to design the circuits of the dual channel low noise amplifiers,the power amplifier,and the dual channel mixers.It also uses the actual fabrication and testing to verify the results of the design.This work is as follows:First of all,this thesis analyses the basic structures of the Beidou dual mode RF front system.It also confirms the basic performance indicators of the dual mode RF front system of Beidou,and distributes the indicators of each functional module according to the analysis.The key indicators include the dual channel low noise amplifier's noise figure,the RDSS emission channel power amplifier's transmitting power,the RDSS emission channel's modulation phase error and IQ offset,and the dual channel mixer's gain and noise.Second of all,this thesis focuses on the analysis of the low noise amplifier and the power amplifier.It also finishes the scheme selections of the low noise amplifier and the power amplifier.In order to ensure that the gain of the RDSS receiver channel low noise amplifier meets the requirements of system and obligates a sufficient margin,the low noise amplifier is designed into two stages.The design of the RNSS LNA is the same as the RDSS LNA.The power amplifier of the RDSS transmission channel uses a driving amplifier of conventional GaAs process and a LDMOS to design.Last but not the least,depending on the requirements of the structure and each module,this thesis uses the computer-aided designed tools to design the low noise amplifier,power amplifier and the dual channel mixer.After completing the circuit board processing,the thesis also tests the actual circuit.The actual test results show that the design of the RDSS receiver channel low noise amplifier's noise figure is 1.524dB and the gain is 24.954dB;the RNSS receiver channel low noise amplifier's noise figure is 1.503dB and the gain is 28.440dB;the RDSS launch the transmitting power of channel power amplifier is 37.436dBm and the gain is 37.436dB,which meets the basic requirements of the Beidou dual mode RF front system.The practical application shows the performance of the RF front system of Beidou is more consistency,small,stable and reliable.