High precision digital trigger method in 20GSPS high speed acquisition system

As the frequency of the electrical signal becomes higher and higher, the timing margin of the electrical signal becomes smaller and smaller, requiring higher and higher acquisition performance of the acquisition system, as well as higher accuracy, smaller jitter and stronger noise immunity of the trigger. Analog triggering has low accuracy and poor noise immunity due to the non-consistency of analog signal transmission delay, non-linearity of analog devices and random noise introduced by environmental factors. Therefore, this paper presents a high-precision digital triggering method synchronized with the sampled data source. The method performs real-time data processing in the digital domain, which not only ensures real-time triggering, but also improves the accuracy of triggering as the sampling rate increases and reduces triggering jitter. The method has been applied and implemented in a 20GSPS high-speed acquisition system, and after testing, the trigger jitter is 50ps at 20GSPS sampling rate; the input superimposed noisy sine wave signal has a stable trigger point and strong noise rejection capability, in line with the effect. The digital trigger system can be commonly used in other acquisition systems that require precise synchronization applications.