Development Of Frequency Conversion And Excitation Circuit For C Band Transmitter

As human society enters the information age,wireless communication technology develops rapidly.Undoubtedly,the development of radio frequency and microwave communication technology plays a decisive role in wireless communication technology field.RF transmitters also play an important role in various fields of the application of microwave technologies.According to the demand of a actual project,a transmitter by using the dual upconversion method have been designed.Since the structure of dual up-conversion is adopted,the reares two mixers.How to realize the high spurious suppression and high port isolation are the key points this work.Upon RF front-end design experience domestic and abroad,as well as the performance and parameters,requirem,a C band transmitter is designed in this paper.Following sare the main contents:Firstly,the common structure and working principle of RF transmitters are introduced,and their advantages and disadvantages are annalyzed.Proposed plans and design requirements are listed implementation methods of some indicators are also analyzed.Secondly,the features of RF transceiver systems are described to highlight which factor contribute mostly to output performances.Performances for RF transceiver are also addressed detailedly and theoretical analysis are further carried out.Thirdly,system again,harmonics and suppression of spuriousare carried out.using ADS,simulation.T simulatied in HFSS.Performance of elements are also descripted.To guarantee the superior performance of the transmitter,reasonable amplifiers,mixers and filters arechoosed to ensure an excellent harmonic and spurious suppression.Transmitter's system layout and microwave cavity are drew using AutoCAD,swich driver and power supply PCB are drew with Designer Altium.Upon these,problems encountered are analysed,and corresponding solutions are put forward.Finally,we use the high temperature soldering tin to weld components,and use the low temperature solder tin to weld the PCB on the cavity.Test results show that the output power of motivation port is 10 dBm,the tested output is 0dBm.And the isolation between input switches are greater than 70 dB,the isolation between 1LO port and 2LO port is greater than 80 dB.The suppression of spurious is higher than 70 dBc,the harmonic suppression can reach 50 dBc,the indices are fulfiled.