Method of High-Precision Digital Slope-Trigger in High-Speed Data Acquisition System

In the field of signal detection applications, the trigger system in the high-speed data acquisition system needs to detect the specific slope characteristics in real-time. In addition, the system must identify signals with slope changes of one sampled data accurately. However, there is a conflict between the high throughput of sampled data and real-time data processing. Therefore, a high-precision digital slope-trigger method based on parallel correlation judgment is proposed in this article to resolve the problem. The proposed method converts large bit-width sampled data into smaller bit-width characteristic data which carries signal edge characteristics. Then, the method determines whether the signal satisfies the specific slope features based on an algorithm that replaces complex math operations with simple logic operations, reducing the volume of data processed in real-time. The proposed method ensures high precision performance of slope-trigger. The article implements the high-precision digital slope-trigger method on a data acquisition system with a 20 GSa/s sampling rate and 8-GHz bandwidth. The implementation results verify that the precision of the slope-trigger achieves 50 ps, which is currently the highest precision among FPGA-based real-time slope-trigger. The proposed method can be extensively employed in high-speed real-time acquisition systems that require the detection of signal slope variations.