Study On Optoelectronic Detection Scheme For Photonic Analog-to-digital Converter

Analog-to-digital convertor is the key component in the process of converting analog signal to digital signal.As the signal processing has an increasing requirement on bandwidth and accuracy,higher demands are placed on the sampling rate and accuracy of analog-to-digital converters(ADCs).Electronic analog-to-digital converter(eADC)performance has been closed to the “electronic bottleneck”,it is difficult to improve the performance of eADC further.ADCs combined with photonics technology possess the advantages of boarder bandwidth and higher accuracy,and provide a novel solution to improve the performance of ADCs.In the photonic analog-to-digital conversion(PADC)system,due to the non-negative characteristic of sampling pulse,the signal obtained directly by the photodetector contains a lot of DC-carrying component.The DC-carrying component takes up part of the back-end quantization range and seriously deteriorates the performance of PADC.The application of balanced-detection on PADC system can make the DC-carrying component cancel,thus making full use of the back-end quantization range.However,the asymmetry in the gain and time delay of the two input paths of the balanced photodetector will affect the performance of the PADC system.In this paper,the PADC system based on balanced-detection technology is studied and its working principle is expounded.The influence of the asymmetry of the input path of the balanced detector on the system performance is analyzed and verified by experiments.First,the principle of photoelectric conversion,the parameters of photodetector and the design of related circuits are introduced,and the noise of photodetector in TIPADC system is analyzed in detail.The working principle of balanced detection technique is introduced.The optical analog-to-digital conversion system based on balanced detection is analyzed theoretically.The relationships between the system ENOB and the input path of the balanced detector is given.Secondly,this paper introduces the simulation structure of optical analog-to-digital conversion system based on balanced detection technology,and explains the process of system simulation with simulation structure,and analyzes the optical analog-to-digital conversion system under ideal conditions.The effects of inconsistency of gain,delay of PD,bandwidth of PD and inconsistent response of PD are analyzed as well.Finally,two-channel experimental platform of optical analog-to-digital conversion system based on balance detection technology is introduced and the corresponding experimental results are presented.For the two-input path of balance detector in optical analog-digital conversion system based on balanced detection,The influence of the inconsistency on the performance of the system is analyzed,and some simulation results are verified by experiments.