Research And Design Of High Precision Pulse Delay Generator For Ultra High Speed Framing Camera

Ultra high speed framing camera is an effective tool to study the transient optical,has been widely applicated in the aerospace, military, scientific research, medical,industrial applications and many other fields. Due to various extreme conditions, theperformance requirements of the ultra-high speed framing camera are increasinglydemanded. High speed, high precision and miniaturization are the main tendency of theultra high speed framing camera. As the core part of ultra-high speed framing camera,the shutter control circuit composed of the pulse delay generator determines theperformance of ultra-high speed framing camera and the realization of the keyindicators. So the design of a high precision pulse delay generator becomes the urgentmatter.This thesis discusses several pulse delay generator designs, and analyzes theiradvantages and disadvantages. In view of the problems of signal synchronization, largedelay jitter in each channel and low resolution of delay time, existing in the currentpulse delay generator of ultra-high speed framing camera. We propose a method toapply digital delay in combination with analog time delay. The long time delay with theresolution of10ns is realized by using counting method of ultra-large scale logic deviceFPGA.The analog time delay circuit composed of the current feedback amplifierachieves the short time delay resolution of1ns. The system uses PIC as the corecontroller, the trigger jitter time measurement circuit uses the current integral method tomeasure trigger jitter time, together with analog time delay circuit and output circuit,make up the trigger jitter compensation circuit to eliminate trigger jitter time, the outputbooster circuit generates a delay signal with+12V voltage and1.3ns rising edge finally.The design complete the pulse delay generator, which is composed of single chipmicrocomputer control circuit, high precision constant current source, trigger jitter timemeasurement circuit, analog time delay circuit, comparision output circuit, boosteroutput circuit, digital delay circuit and data communication modules. We analyse theperformance of the ECL current switch and the diode, the precision, stability andinherent time of the pulse delay generator, the solution to improve the system acuuracy and stability is found,The creative point of this thesis is the trigger jitter time measurement circuit basedon the principle of current integral, which is composed of ECL charging current switch,high speed diode, charging capacitor and operational amplifier. The external triggerjitter time can be converted and stored in voltage form by the trigger jitter timemeasurement circuit. In this way, the measurement result is more precise and thestorage time is longer. The trigger jitter compensation circuit composed of trigger jittertime measurement circuit, analog time delay circuit and output circuit of trigge, is usedto eliminate trigger jitter, the trigger jitter time of system can be controlled under1ns.The test of the high precise pulse dilay generator show that the design solution iscorrect and workable, and the performance of each module can meet the requirements ofdesign index. The high precise pulse delay generator has the advantages of high timeresolution, low time jitter, short rising time of output pulse, high reliability and stability.