Research On Rfreceiver Front-endcircuits Of MIMO Satellite Communications Systems

Because of its irreplaceable position, satellite communications systems are widely used in military and civilian fields. High-speed and high-quality data transmission puts forward higher requirements for transmission bandwidth of satellite communications. Multiple-input Multiple-output(MIMO) technology has achieved great success in improving the spectrum bandwidth of terrestrial wireless communications. In this paper, MIMO technology is used in satellite communications, and a RF receiver front-end circuit is designed and implemented.Decades of continuous researches make RF receiver circuits develop several common topologies. The super-heterodyne architecture is use dafter comparison and comprehensive consideration. By theoretically explaining and analyzing the main specifications of the receiver and technical requirements of the task, this paper gives the overall design solutions of the RF front-end circuit.Located in the most front end, low-noise amplifier’s performance has a direct impact on the overall index of the receiver. ADS software is used to design a low noise amplifier with high gain and linearity in a small current, finely meeting the requirements of the system. Local Oscillator(LO) is an important component of the receiver circuit; a frequency synthesizer is designed based on theory of phase locked loop as the receiver local oscillator signal source. Isolation between each channel of multi-channel receiver is a significant indicator to characterize system performance, the factors that influence the channel isolation are analyzed, and the specific methods to improve channel isolation are given. These methods play a very good role in circuit designing and debugging.Finally, the main devices are debugged and tested, and the overall receiver is experimentally verified. The indicators meet the requirements at room temperature. During high and low temperature experiments, the system appears self-excited phenomenon at low temperatures. After investigation, and the cause of the self-excited is ultimately determined, and the problem is solved successfully.