Research Of Waveform Digitization With Switched-Capacitor Arrays

Waveform digitization offers the experimenter the maximum possible information of the pulse from detectors. The arrival time and charge information can be easily extracted from the waveform. Traditionally we use Flash ADC for digitization; however such systems suffer from low channel densities, huge power comsuption, as well as high finicial cost. An alternative to flash ADCs is the switched-capacitor arrays (SCAs). Detector signals are sampled and stored in an array of fast capacitors at a very high speed, and digitized with a commercial ADC at a lower rate before a new waveform is acquired.Up to the present, several Application Specific Integrated Circuits (ASICs) have been developed abroad. Some of the representatives are as Domino Ring Sampler from Paul Scherrer Institute (PSI), Switzerland, and Analogue Ring Sampler (ARS) in ANTARES neutrino telescope, about40km off the Frech Riviera coast near Toulon. Currently we donot find any reports about waveform digitization with SCAs at home. In this thesis, we present the research of waveform digitization with DRS4, the fourth version of DRS, as well as its application in particle physics experiments. This thesis is arranged as follows.In chapter1, we discussed the trend of front-end electronics in future particle experiments. There is gaining evidence that waveform digitization will play an important role in front-end electronics in the next two decades. At first, Flash ADCs were widely used for digitization since the1980s, but they are now replaced by SCAs to meet the increasing requirements of nowadays particle experiments. We also gave experiments ultizing FADCs and SCAs for example in this chapter.In chapter2, we presented the various techniques of realization of current available SCAs. We tried to classify them and gave introductions of their implementation and characterization according to their catalog. Finally, we summarized our classification and gave the tendency of the next gereration of SCAs.In chapter3, we introduced the implementation of our two versions of waveform digitization system with DRS4. In Chapter4, we showed the performance of the waveform digitization systems. We developed a series of calibration strategies as DC offset compensation and uneven sampling intervals calibration. We also evaluated the timing performance of the system and the interleaved sampling scheme of analog channels of DRS4with PCB routing delay on board. Generally, the timing performance of the system is as low as10ps after calibration and we achieved about10GS/s with2channels interleaved.In chapter5, we put the waveform digization system into one of our physics experiments. We tried to extract the timing information of detector signals from their waveform and compared different timing techniques. We also gave our consideration of the extraction of the charge from the sampled waveform.Finally, in chapter6, we conclude this thesis and summarize what have been achieved.