A novel method for PAM-4 signal quality estimation using asynchronous eye diagram reconstruction

We present a simple and low-cost method for estimating the symbol error rate (SER) and bit error rate (BER) for 4-ary pulse amplitude modulation (PAM-4) signals from the reconstructed eye diagrams obtained by using asynchronous sampling technique. The reconstructed PAM-4 eye diagram is divided into three separate sub-eyes. The optimal sampling position of the signal phase is obtained by overlapping these three sub-eyes to locate the time instance with the largest eye-opening. The calculated SER and BER are close to the simulated results.