Design And Research Of LTCC Miniaturized High Power Filter Module For 5G Base Station

With the development and upgrading of the new generation of information technology,in wireless communication,the base station equipment is gradually developing towards the trend of integration and miniaturization,especially since the commercialization of 5G mobile communication,the integration of base station RF circuits with filters as the main building blocks is getting higher and higher.Since the number of RF filters in 5G Massive MIMO antenna systems is in the hundreds and thousands,it’s obvious that the traditional cavity filters and dielectric filters have gradually become difficult to meet the development needs of 5G base stations.In recent years,communication RF devices based on low-temperature co-fired ceramic(LTCC)process,with their smaller size and stable performance,have emerged in the era of 5G communication and become a research hotspot pursued by the industry.This paper adopts LTCC process to design RF filters in 5G base stations,and conducts research on filter miniaturization,multi-functional module construction,and electro-thermal coupling analysis of devices under high power.While gradually improving the degree of integration of the device,to ensure its low insertion loss,high out-of-band rejection performance indicators.In order to achieve the goal of enhancing the power capacity of the device under high power,the heat dissipation structure of the device is designed.The specific research is divided into the following parts:(1)A 5G LTCC band-pass filter which based on comb-line filter design theory and applied to 5G micro base station communication equipment is designed.The filter’s working frequency band covers 3300 to 3600 MHz,and pass-band edge attenuation of 200 MHz greater than 30 d B.The filter uses a fifth-order resonator structure and introduces cross-coupling in the first and fourth order to improve out-of-band rejection,which with better performance and smaller size of 9 mm×4.5 mm×0.96 mm.The physical test results show that the filter performance basically meets the requirements of the index.(2)A Wi-Fi 6 band-pass filter which made of lumped LC capacitors and inductors and applied to 5G Wi-Fi is designed.The filter’s working frequency band covers 5150 to 5950 MHz.In the design process of this filter,the influence of internal parasitic parameters is fully considered and rationally utilized to achieve the goal of filter miniaturization and low insertion loss,finally the overall size of the filter is only 1.6 mm×0.8 mm×0.6 mm.(3)A multi-functional RF module is designed under the application requirements of 5G base station equipment,which consists of filter,power divider and coupler coupling.The filter is obtained by adjusting the structure of the first band-pass filter,the coupler adopts the coupling ribbon line structure,which is the side coupling of the same plane,the power divider adopts collective element type power divider,which reduces the size by resonant structure.The module has a reasonable allocation of internal space to reduce the electromagnetic coupling interference between each other.The module can choose different working modes by controlling the connection and disconnection of external pins according to equipment requirements,which has the characteristics of switchable functions.The module has high performance and small size which is only 10 mm×6.9 mm×1.92 mm.The integration of RF passive devices and module miniaturization are realized,and the physical test results show that the performance of the multifunctional filter module meets the design specifications.(4)Based on Icepak software,the electro-thermal simulation and analysis of the designed filter and RF module are carried out.Meanwhile,the thermal performance of the device in terms of substrate material,device structure,and external heat sink are discussed.Several heat dissipation improvement schemes are proposed to improve the power capacity of the device by combining heat dissipation theory,and verified by software simulation at the same time.Finally,several thermal improvement options are compared and analyzed.