Research Of Hybrid Optical/Electronic Analog-to-digital Conversion Based On Opticai Sampling And Multi-channel Processing

Digital signal has many incomparable advantages at signal transmission and processing that analog signal can’t compare with. As a key component converting analog signals into digital signals, the ADCs’(Analog to Digital Converter, ADC)performance directly affects the entire digital signal processing system. Due to limitations of physical bottlenecks, traditional electronic ADCs can’t meet the growing speed and accuracy requirements. However, the use of optical methods can effectively break the bottlenecks of physical electronic ADCs. Implementing optical methods in electronic ADCs is considered to be effective way to achieve both high-speed and high-precision in analog to digital conversion.An optical analog-to-digital system based on optical sampling and multi-channel processing is simulated in this thesis. Specific work as follows: Firstly, a four channels and 4.2GS/s’ sampling frequency optical ADC system is built in simulation software.20 GHz analog signal is tested on the system and achieve the effective number of bits of3.95. This proves the ability of the system to achieve the bandpass signal digitalizaion.Secondly, the multi-channel consistency is discussed, including the pulse amplitude and pulse timing between channels and the clock of rear electronic ADCs. Tolerable error range of multi-channel consistency has been achieved. An optimization algorithm to improve signal quality has been proposed and verified by simulation. Thirdly, the influence of modulation depth is discussed. It shows that modulation depth is vital to the accuracy of ADC system and ADC system have optimal modulation depth. At last,dispersion, modulator transfer function and modulator bias point drift’s effects on signal accuracy are discussed. Non-linear distortion on signal is corrected by using complementary modulation and arcsin function operation, the effective number of bits is raised up to 5.72.A dual-channel optoelectronic hybrid analog-digital conversion system based on optical sampling is built in this thesis. Specific work as follows: selection of experimental equipment, parameters measurement, time and wavelength sampling light sequences interleaving generation(2 × 27.43MHz) and dual-channel electronic ADC clock match. 200 MHz signal is tested on the system and a precision of 1.48 analog to digital conversion is achieved. The causes of experimental platform ADC with lowprecision are analyzed. Finally, the optimization operation discussed in simulation part is implemented on the signal, and the effective number of bits is raised up to 2.23.