LTCC Radar Receiver Front - End Design And Implementation

A low-temperature cofired ceramic (LTCC) radar receiver front-end module is designed and realized in this paper. The process of circuit design and realization is elaborated in the following three aspects respectively: the selection of overall plan, the design and realization of passive circuits and that of active circuits.1. In this paper, the two-channel-quadrature-output superheterodyne receiver front-end is selected as the overall plan. The circuit indexs of each circuit component are allocated and subsequently the components are selected. A system simulation of the whole receiver front-end module is performed and the simulation result is: gain 42.53dB, switch isolation 86dB, noise figure 1.9dB. This result satisfies the expected value.2. The design method of LTCC passive circuits is mainly researched in this article.A novel multilayered LTCC microwave bandpass filter is proposed and realized. The filter is composed ofλ/4 stepped-impedance resonators ( SIR ) , which are arranged as a rotate-symmetry structure on two layers respectively. Such an arrangement can reduce the filter size and suppress harmonics effectively. The other microwave passive components such as the splitter, the 3dB90°directional coupler are also designed with 3D multilayered structures, increasing the integration density of the module effectively. Simulation and tolerance analysis of all the passive components are made by 3D electromagnetic field simulation software HFSS, and then, all the passive components are fabricated and tested. The test results accord with the simulation results approximately.3. As to the active circuits, the microwave limiter, RF amplifiers, microwave switches, IQ quadrature modulator, IF amplifiers and so on are designed and realized in this paper.Finally, the whole receiver front-end module is fabricated and tested. The test result is: the gains of the two channels are 38.33dB,36.18dB, switch isolations are 77.5dB,76.8dB, and noise figures are , the results show that the performance of the module achieves the expected target.