Dear Dr. Stefan Ritt

I am writing to seek your advice regarding an issue I encountered while using the DRS4 chip in ROI (Region of Interest) readout mode to sample waveforms. My name is Qichao Wu, and I have been working with the DRS4 for waveform sampling.

In my setup, I input two identical sine waves (with a period of 250 ns and the same phase) into two different channels of the same DRS4 chip. Ideally, the waveforms acquired from both channels should completely overlap, as shown in Figure 1. However, I occasionally observe that the waveform from one of the channels is truncated. The truncated portion appears to originate from a different segment of the input signal, resulting in only partial overlap between the two channels. This phenomenon is illustrated in Figure 1. Additionally, there are instances where both channels exhibit truncation simultaneously, as depicted in Figure 2.

I have confirmed this issue by observing the truncated waveforms directly on an oscilloscope when the DRS4 is operated in ROI mode. Notably, the truncation points always occur near cell 0 and cell 1023 of the DRS4 switch array.

Could you kindly provide guidance on how to resolve or mitigate this issue? Any suggestions or insights you could offer would be greatly appreciated.

I look forward to your positive response and thank you in advance for your time and assistance.

Best regards,
Qichao Wu