Digital System Design Of VXI High Speed Oscilloscope Module

The 21 st century is an era of rapid development of science and technology.The development of science and technology has promoted the application of high-frequency circuits in the electronics industry,and has also promoted the market application of high-speed oscilloscopes.And engineers are increasingly demanding powerful oscilloscopes,and major manufacturers are working hard to increase the capabilities of the oscilloscope.Therefore,this topic is mainly aimed at the research of the function of the digital system module of high-speed oscilloscope.This topic is based on the VXI bus oscilloscope module,and conducts in-depth research on VXI bus interface circuit,trigger and data storage,and random equivalent sampling technology.The main work includes the following parts:(1)VXI bus interface circuit design.In the field of automatic testing,the emergence of a virtual instrument platform based on the bus method greatly simplifies the development difficulty,and is very important for the research of the bus.This part mainly studies the design principle and implementation method of VXI bus interface.The VXI bus register base and message base interface technology are studied.The design scheme of VXI bus hardware circuit and logic circuit is given.(2)Trigger and data storage design.The trigger sources included in this part include channel trigger,external trigger,VXI bus trigger,etc.,and adopt various trigger types such as edge trigger,pulse width trigger,ARM trigger and pattern trigger.Memory depth is an important indicator of an oscilloscope and represents the ability of an oscilloscope to continuously store waveforms.An oscilloscope with a large storage capacity can observe more waveforms.This topic mainly studies the control logic of DDR3 SDRAM memory sticks.The controller mainly realizes the correct reading and writing of data from DDR3.In addition,the FIFO and the trigger signal are used to effectively divide the storage space,and the segmentation storage function is realized,so that more effective waveform data can be stored.(3)Random equivalent sampling control circuit design.The random equivalent sampling technique adopted in this subject is to reconstruct the data after multiple sampling in the chronological order in the FPGA and then store it in the preset memory.After the multiple samples are used to store the memory,the memory is extracted.The reconstructed waveform is displayed.Reconstructing the waveform using FPGA can greatly improve the waveform refresh rate.In the random equivalent sampling module,the time interval ?t from the trigger point to the rising edge of the first sampling clock determines the position of each sampling point in the memory,so the accuracy of the measurement of the time interval ?t is very important.This paper analyzes the error characteristics of the pulse stretching circuit and uses the method of piecewise fitting to achieve more accurate time measurement.The digital system based on the VXI bus high-speed oscilloscope designed by this subject realizes the waveform reconstruction of the maximum equivalent sampling rate of 200 GSPS in the FPGA.In deep storage mode,the storage depth of a single channel of 256 Mpts can be realized,and the segmentation storage function is realized.