Study On Signal Correction For Time-wavelength Interleaved Photonic Analog-to-ditigal Conversion

Analog-to-digital converter (ADC) is the device that converts analogsignal into digital signal. As the bandwidth and accuracy requirement ofsignal processing in communication and research rises, ADCs with highersampling rate and efficient number-of-bits (ENOB) are expected. Also theprogressive digital signal processing and storage technology supportsADC’s development. The electronic ADCs’ bandwidth and accuracy haveraise a lot among decades of researching, but it will be hard to improvedramatically according to the limitation of electronic bottleneck on timingjitter.According to the benefits on large bandwidth and high stable,photonics has been induced into ADC research to improve ADC’sperformance. Several scheme of photonic ADC (PADC) system have beenproposed including time-wavelength interleaved, time-stretch and so on,their sampling rate and ENOB are also improving. Current research onPADC mainly includes system scheme, component fabrication, and signalcorrection.This thesis mainly studies signal correction in time-wavelengthinterleaved PADC (TIPADC). Theory of TIPADC scheme is analyzed.Mathematical model of noise and distortion induced by opticalcomponents is made and their influence on system accuracy is investigated.A correction process based on calibration is designed according to themodel. The noise characteristics of optical time division multiplexing(OTDM) module is analyzed and simulated. A correction process based onadaptive noise cancelling is designed and realized by simulation and experiment.First, in this thesis the principle of TIPADC is introduced and anmathematical model is made. Noise characteristics of mode-lock laser,mismatch among channels and non-ideality of electronic-optical modulator(EOM) are analyzed. Their influence on system’s ENOB is also studied.Secondly, a correction process based on calibration is developed. Bygiving the system a certain signal and analysis the sampling result, thefeature of system can be calculated. The calibration methods of differentcoefficients such as mismatch among channels, sin-1coefficient and EOMcoefficient are different. They are designed by the mathematical model wehave made. Simulation of this correction process on a system with8GS/ssampling rate is made and ENOB of6.4bit is achieved.Finally, feature of OTDM module is studied and its influence onsystem accuracy is also analyzed. As OTDM induced noise can be detected,the adaptive noise cancelling in digital signal processing is induced intocorrection. The scheme of this correction process is designed andsimulation of single channel and multi-channel system is made. Inmulti-channel system, the combination of calibration and adaptive noisecancelling is investigated to correct both inter-channel noise and OTDMinduced noise. Simulation results proved the efficiency of this method.Experiment of single channel system is made,12dB improvement of signalto noise and distortion (SINAD) is achieved on a system with4.66GS/ssampling rate.