Research Of Low Power Digital Correlator Based On ASIC In FPIR System

Interferometric radiometer is composed of small antennas. By cross correlation between a pair of antennas, a large aperture is formed. Therefore angular resolution, which is proportional to the antenna aperture, is improved. Nowadays, microwave interferometric radiometer is well applied in the field of atmospheric, oceanic and terrestrial remote sensing, etc. Full polarization interferometric radiometer(FPIR) is a one-dimensional microwave interferometric radiometer with high resolution, light weight and low power consumption. FPIR combines the interferometric synthetic aperture imaging technology and fully polarimetric parameters information acquisition. Compared with the conventional one-dimensional synthetic aperture microwave radiometer, the advantages of FPIR are fully polarimetric information acquisition, conical antenna beams and two-points calibration, etc. The ultimate objective of FPIR is to achieve the spaceborne applications. In spaceborne applications, excessive power dissipation may result in temperature control, reliability, and other aspects of problems, and also put forward higher requirements on the satellite platform. In order to meet the demands of spaceborne applications, it is necessary to control the system power consumption strictly. Digital correlator is a key component and the largest power consumption module of the FPIR system, so, the design of low power digital correlator is an important part to guarantee low power consumption of the payload.In the current study of microwave interferometric radiometer, there are two main approaches to accomplish the design of digital correlator, FPGA and ASIC. FPGA is mainly applied to the digital correlators of prototypes and airborne systems; ASIC is usually used to the digital correlators of spaceborne applications. In the current domestic studies of microwave interferometric radiometer, the designs of digital correlator are only based on FPGA. With the development of microwave interferometric radiometer and the demands of low power consumption in spaceborne applications, the study of the digital correlator based on ASIC is urgent and needful. This thesis is about the study of the design of a low power digital correlator based on ASIC. The purpose of this thesis is to design a low power digital correlator in FPIR system in the premise of ensuring the performance of digital correlator system, and lay a foundation for the subsequent spaceborne engineering. The main work of this thesis is as follows:(1) Based on the basic structure of FPIR system, analyzed the principle, structure and data processing flow of digital correlator in FPIR system. According to the design specifications, analyzed the implementation algorithms of different parts of the digital correlator and the imperfection of the amplitude and phase caused by digital correlator.(2) Based on the analysis of implementation algorithms of digital correlator, completed the RTL design of digital correlator according to the design specifications of FPIR principle prototype, and completed the RTL design of the calibration of amplitude and phase errors.(3) Researched the design method of structured ASIC, designed a digital correlator based on Hard Copy ASIC, and performed functional simulation and power analysis.(4) In the FPGA prototype module of digital correlator in FPIR system, completed FPGA prototype verification of the RTL design, verified the logic function of RTL design is consistent with the algorithm, and realized amplitude and phase calibration.