Research On Low Noise Imaging Circuit Technology Of CCD Based On FPGA

In the continuous exploration of the universe,the search for planets outside the solar system has become a hot spot in the study of international astronomy.Obtaining images of extrasolar planets is an indirect evidence of their existence,as a prelude to broader spectral studies,and as a first step toward the long-term future of analytical space imaging for obtaining extrasolar planet surfaces.Therefore,CCD is an important carrier for image acquisition of extrasolar planets,and its research and use will have important scientific significance.Based on the project index requirements and the working principle of CCD imaging,this paper designs a full frame transfer type scientific CCD(TH7888A)low noise imaging system based on FPGA.The research work mainly includes the hardware circuit design of CCD low noise imaging system and the generation of its driving timing.The specific research contents are as follows: 1)Designed an FPGA-based CCD low noise readout circuit design.The readout circuit of the imaging system was designed and simulated by using Proteus.The signal-to-noise ratio of the low-noise readout circuit is calculated and the rationality of the design of the imaging circuit is verified.2)A scientific-grade CCD low-noise imaging circuit with simple structure and stable performance is designed.The low-noise imaging circuit designed by E2V's scientific CCD(TH7888A)as the core device of the imaging system includes: CCD peripheral circuit,AD peripheral circuit,low noise power generation circuit,Camera Link hardware interface circuit and other processing modules.Through the coordination of each module,the hardware environment of signal processing is built.3)An FPGA-based low noise timing signal generation module is designed.The timing generation module of the CCD low-noise imaging system mainly includes: the driving timing of the TH7888 A,the register configuration timing and sampling timing of the AD,and the configuration of the FIFO memory.According to the working sequence logic relationship between each module,the corresponding logic design is carried out to finally obtain the required correlated low noise logic clock signal.4)Experimental verification of the entire low noise imaging circuit.A test platform was built in the actual environment,and the hardware circuit of the imaging system and the low-noise logic timing were tested in detail.The experimental results show that each functional module circuit realizes the design requirements,and the generated low-noise logic timing also meets the actual requirements,and finally realizes the real-time transmission and display of image data.