Research On The Design Of 30MHz-8GHz Wideband Receiver Front-end

The rapid development of wireless communication has led to the increasing use of frequency bands below 8GHz.In addition to 3G and 4G mobile communications applications,3300-3600 MHz,4800-5000 MHz band is expected to be the first 5G band and WIFI uses 2.4 GHz and 5.8 GHz band in China.Therefore demands for RF testing and spectrum monitoring are increasing.The frequency band for monitoring is also getting wider.In this dissertation,a RF receiver front-end of 30MHz-8GHz is designed for applications of RF testing and spectrum monitoring.The main work of this dissertation are as follows:1.A 30MHz-8GHz RF receiver front-end is designed.In view of the technical difficulties such as the wide frequency band,the interference of image frequency component,the large number of RF filters and the large size of the structure,several RF receiver front-end structures are compared and studied.Through adoptting two-stage mixing and multiple sub-band superheterodyne receiver structure,optimizing the mixing strategy,reducing the image frequency interference components,this dissertation realize the miniaturization of the receiver front-end.2.Solve three key technical issues of the broadband RF receiver: image frequency interference,high dynamic range and miniaturization of the receiver.By subdividing the sub-bands reasonably,designing the low-pass filter with low temperature co-fired ceramic chips,designing the band-pass filter with microstrip interdigital filter,the image rejection is up to 70 dB and the size of the RF front-end circuit significantly reduces.The size of the front-end is 170 mm * 70 mm * 17 mm.By hierarchical gain adjustment method and gain control circuits which are added in the RF circuits and IF circuits,the RF receiver achieves a 70 dB receive gain adjustable range and improves input dynamic range.3.Simulation and testing of the 30MHz-8GHz RF receiver is completed.The system structure and IC are selected by ADS simulation on RF chain gain,mixer component,noise figure and other RF parameters.Image rejection microstrip filter banks are simulated and optimized by CST.In this paper,the wideband RF receiver front-end greatly improve the convenience of RF testing and spectrum monitoring.It can be used for general laboratory testing and base station spectrum fixing and mobile monitoring.Because of its wide bandwidth and small size,it is especially suitable for spectrum monitoring applications using the UAV platform.