Research On Multi-Channel ADC Calibration Technology Of Ultra-High Speed Optical Signal Acquisition System

In modern communication system,the analog-to-digital converter(ADC)plays an important role,especially in the field of digital coherent communication.The demodu-lated signal can enter the digital domain through ADC.However,due to the mismatch of ADC,the sampled signal has been damaged to varying degrees,and the output results de-viate from the ideal sampling points,which seriously affects the subsequent digital signal processing and cannot restore the network information required by the user.Therefore,the calibration of the ADC is very important for the subsequent signal processing.In view of the above problems,the research content of this article mainly includes the following points:1.For the preliminary calibration of the ADC in the acquisition system,a Monte Carlo method is proposed to estimate the mismatch between channels,and on this basis,the channel equalization method is used to calibrate the mismatch parameters to elimi-nate static errors? secondly,an iterative estimation structure is designed to continuously approach the true value of the time delay,and use the reconstruction filter to calibrate the distorted signal,harmonics are effectively suppressed.2.Online calibration of Time-Interleaved ADC has been researched.The random-ization of the input signal and the two-point method to calibrate the static error of the ADC are proposed.The channel correlation is used to compensate the delay generated by the sampling clock.The relative error of the estimation algorithm is low,and the signal quality after calibration is significantly improved,the signal quality after calibration has been significantly improved.3.In the hardware test stage,a synchronization algorithm for FPGA high-speed channels is proposed.The algorithm uses the training sequence to correct the offset be-tween the channels,the input signal is compared with the pseudo-random sequence,and the read address and shift of the RAM are adaptively adjusted.Finally,the synchronous transmission of 4 ADCs is realized,lay the foundation for the hardware implementation of the calibration algorithm.