A Novel Method for ADC Channel Alignment in Optical Signal Reception System

In the coherent optical transmission system, the analog-to-digital converter (ADC) plays an important role to transfer the analog signal into the digital domain for the subsequent processing, but there may be mismatch and affect the signal quality, so channel synchronization is essential in the system. This article presents a method to synchronize the 4 ADCs, we use the pseudo-random binary sequence (PRBS) code to detect the mismatch in the descramble process, and feedback asynchronous information to the relevant register, the random-access memory (RAM) outputs different bits depending on the address of the feedback, after several iterations and adjustments, 16 channels are aligned, ADC is able to sample at the same time interval, lays the foundation for subsequent dispersion compensation, modulation format identification and decision. Such method does not need additional circuits, the structure is simple and the convergence is fast, work in the background mode, there is no impact on the ADC conversion.