Real-Time Digital Baseline Restoration for CCD Sensors With Implementation in FPGA

Charge-coupled device (CCD) sensors are the primary imaging sensors in scientific astronomical cameras, known for their exceptional channel uniformity. However, the unavoidable baseline drift during alternating current (ac) coupling leads to inconsistencies among pixels in the row direction, especially during high-speed readouts. Standard corrections are insufficient, posing challenges to astronomical observations. The digital correlated double sampling (DCDS) technology enables digital signal processing (DSP) for CCD readout. A real-time digital baseline restoration method was developed and implemented in a field-programmable gate array (FPGA). This method overcomes traditional limitations and can eliminate baseline drift error effectively. Furthermore, the performance of this method in terms of readout noise, channel gain, and nonlinearity was tested, confirming its potential for compensating for baseline drift error in scientific applications.