CCD读出电路中数字补偿式一阶模拟滤波器设计

Digital Compensation First-order Lowpass Filter in the CCD Readout Circuit

CCD读出电路中低通滤波器在改善系统输出信噪比的同时,不可避免地会产生像素串扰,造成信息畸变。本文针对CCD读出电路中像素串扰造成的信息畸变问题进行理论分析,推导出信息畸变度与一阶低通模拟滤波器截止频率的关系。并针对视频模拟滤波电路中高阶滤波器的实现困难,提出一种数字补偿式一阶低通模拟滤波器的设计方法,该方法根据本文对信息畸变理论的分析,采用一阶低通滤波器,在满足信息畸变度的前提下,极大降低系统截止频率,达到了应用系统的带宽要求,从而可以在应用系统设计中以一阶滤波器替代高阶滤波器。并设计实验进行验证,证明了该方法的正确性与有效性。

The lowpass filter in the CCD readout circuit inevitably results in information distortion of pixel crosstalk while improving the system signal-to-noise. To solve the information distortion caused by the pixel crosstalk in the CCD readout circuit, the relation between the information distortion and the cut-off frequency of the first-order lowpass filter was deduced. On the basis of information distortion theory analysis, a new method of digital compensation first-order lowpass filter was proposed to resolve high order filter＇s realization inconvenience. The proposed method adopted first-order lowpass filter to design the CCD readout circuit. The designed first-order filter may greatly reduce the cut-off frequency and at the same time satisfy the system information distortion degree. So the designed first-order filter may be substitute for high order filter in the application system. Finally, the validity and feasibility of the method are verified by the elaborate experiment.