| The excellent performance of receiving front-ends plays a key role in the microwave systems, and it will directly influence the effect of the signal processing. A research in the theory and technology of the receiving front-ends system is made, and a receiving module of Ku band is designed in this dissertation.The major job is realizing a receiving front-ends in Ku band, which has a wide dynamic range of 70dB, and the isolations are nearly higher than 40dB between RF port and LO port, the output power is between 0dBm～5dBm, noise figure is less than 3 dB.According to the requirement and the practical condition, twice conversion and automatic gain control (AGC) have been taken to solve the problem of dynamic range. As the considerations of local oscillator power and isolation, amplifier and isolator have been joined to LO before mixing. MMIC device and packaging device as mixer is adopted in the paper according to the difference of RF frequency. Taking into account the interfaces with the external form, as well as Ku-band frequency characteristics, the SSMA is directly used to extrative microstrip signal.The receiving front-ends is introduced firstly in the dissertation. It analyses and illustrates the characteristic and technical specification of receiving front-ends,. Secondly it presents and designs the realization method of receiving front-ends in order to suggest several design plans of feasibility and possibility.Chapter 2 ,chapter 3 is about solid circuits used in the project, such as amplifiers, mixers, operational amplifiers, filters, isolators, and baluns, involving principles, characteristics and the design. The needed chips are chosen according to the actual circumstances.Chapter 4 is about the realizing of the Ku band receiving front-ends. Provide the design principle of this component according to the specification requirement for this subject, then explain respect of receiving the making, assembly and testing of the component etc. separately.The results of the test demonstrate that the system has a good performance in the dynamic range, isolation, and the amplitude coherence. The electrical performances satisfy the target requirements. |
