研究目的
To calculate an optimal filter for noise reduction in the readout of charge-coupled devices (CCDs) taking into account the charge transfer and feedthroughs due to capacitive coupling in the CCD.
研究成果
A detailed modeling of the video signal and charge transfer characteristic of the output stage of the CCD were presented, including the modeling of the clock feedthroughs. An optimal filter to compute the pixel values, which takes into account the charge transfer characteristic in CCD readout and noise characteristic, was developed. It considers all the samples in the readout, even those in the transition between pedestal and signal levels. The proposed technique gives better noise rejection than the CDS technique for the same filter length or equivalently, a reduction of the pixel-time for the same readout noise.
研究不足
The experimental setup requires precise synchronization between the sequencer that operates the CCD and the digital acquisition of the video signal samples. Future work will focus on computing the pixel values using the complete pixel structure.
1:Experimental Design and Method Selection:
The methodology involves a detailed analysis of the dynamics of the video signal and charge transfer, including the circuital modeling of the output stage of the CCD and the dynamics of the electronics in the video chain before the analog-to-digital (AD) converter.
2:Sample Selection and Data Sources:
Experimental measurements were carried out using a 1248 × 724 pixels Skipper-type CCD.
3:List of Experimental Equipment and Materials:
The readout electronics was developed by the research group and includes an Artix-7 FPGA (XC7A200T), 18-bit, 15 MSPS ADCs (LTC2387), and low-noise differential operational amplifiers (LTC6363).
4:3). Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The video signal is sampled with a sampling frequency Fs = 1∕Ts using an analog-to-digital converter (ADC). The discrete time signal is then used to compute the pixel value.
5:Data Analysis Methods:
The pixel value is computed using filter coefficients that minimize the pixel error produced by the noise signal.
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