Study Of Reflectionless Filters Based On TSV

The continuous development of communication systems has driven technological innovation in the field of communication,and filters,as selectors in communication systems,also have a higher demand.Traditional filters reflect the stopband signal back to the source,which in practical communication applications,especially in 5G communication,can lead to increased intermodulation interference in mixers and gain fluctuations in high gain amplifiers.Non reflective filters can absorb stopband signals to meet the requirements of interference suppression in 5G applications,thus attracting much attention.In recent years,domestic and foreign scholars have proposed various types of non reflective filters with different structures,but they all have the problem of relatively large sizes.With the rapid development of integrated circuits,small size and high performance have become the trend.Therefore,this article combines non reflective filters with TSV(Through Silicon Via)technology to achieve miniaturization and easy integration with good performance.This article proposes a total of 5 non reflective low-pass filter structures based on TSV.Two of them are symmetric structures,and three are complementary duplex structures.For a symmetric structure of a non reflective filter,the basic low-pass filter circuit is modified using the odd and even mode analysis method to make its odd mode and even mode parts completely symmetrical.The reflection coefficient expression is derived through impedance analysis and made to meet the conditions of a non reflective filter.After building the circuit schematic diagram,implement the three-dimensional structure in HFSS(High Frequency Structure Simulator)software.Finally,analyze the error and partial coupling effects to verify the rationality of the symmetric structure non reflection filter based on TSV technology.The two symmetric structures in this article are 0.23×0.186×0.139mm3 and 0.476× 0.422 × 0.194mm3,with S11 having peaks of-14.8dB and-19.6dB.throughout the entire testing frequency band,maintaining good non reflective performance.The latter adjusted the circuit on the basis of the former,optimizing the sideband selectivity and making the transition band steeper.The increase in the number of components resulted in larger sizes,but still at the micron level.For a non reflective filter with a complementary duplex structure,there are two output branches,one low pass and one high pass.The low pass and high pass parts complement each other,and the entire signal will be output separately by the low pass and high pass branches,meeting the non reflective requirements.The low-pass part of the first structure is completely symmetrical with the high-pass part;The second structure adopts an inverse Chebyshev response circuit for the low-pass,and an inverse Chebyshev response complementary circuit for the high-pass;The third structure will adopt a loop form,consisting of two low-pass branches and two high-pass branches,each branch being completely symmetrical.The final dimensions of the constructed three-dimensional structure are 0.3 × 0.238 × 0.188mm3、0.23 × 0.196 ×0.139mm3、0.280 X 0.230 X 0.239mm3 achieved miniaturization of the device.The S11 values throughout the entire testing frequency range are-17.9dB,-13.8dB,and-13.75dB,respectively,exhibiting good non reflective performance.