As the areas of CCD detectors and CCD mosaics have become larger and larger, the number of readout channels in astronomical cameras has increased accordingly to keep the image readout time within an acceptable range. For the large area cameras or the mosaic cameras, the analog Correlated Double Sampling (aCDS) circuit used in traditional astronomical cameras for suppressing readout noise is difficult to integrate into the camera controllers within the constraints of the space and energy consumption. Recently, digital CDS (dCDS) technology has been developed to solve this problem, which also offers novel analysis and noise suppression methods. In this study, a mathematical model is presented to conveniently analyze the frequency characteristic of a dCDS circuit, which is then simulated by a numerical method for investigating the noise suppression capability with different sampling weights. Importantly, using this model, the extreme point with lowest readout noise can be predicted for a certain dCDS model; and for a specific CCD readout frequency, readout noise can be suppressed by selecting the proper dCDS model. A testing system is then constructed for validating the efficiency of the proposed method.

随着CCD探测器和CCD马赛克的面积越来越大，天文相机中的读出通道数也相应增加，以将图像读出时间保持在可接受的范围内。对于大面积相机或马赛克相机，传统天文相机中用于抑制读出噪声的模拟相关双采样（aCDS）电路在空间和能耗的限制下难以集成到相机控制器中。最近，已经开发出数字 CDS (dCDS) 技术来解决这个问题，该技术还提供了新颖的分析和噪声抑制方法。在这项研究中，提出了一个数学模型来方便地分析 dCDS 电路的频率特性，然后通过数值方法对其进行模拟，以研究不同采样权重的噪声抑制能力。重要的是，使用该模型，可以为某个 dCDS 模型预测具有最低读出噪声的极值点；对于特定的 CCD 读出频率，可以通过选择合适的 dCDS 模型来抑制读出噪声。然后构建测试系统以验证所提出方法的效率。