Square QAM transmitter using QPSK modulators driven by binary electrical signals

Abstract

We have proposed a scalable, square QAM transmitter using QPSK and phase modulators. The scheme employs binary electrical signals and generates the desirable Gray coded symbol constellation that minimizes the bit error rate due to symbol errors. The scheme can be tolerant to dispersion-induced ISI due to the straight line symbol transitions from the binary-driven QPSK modulators.