Differential quadrature phase shift keying (DQPSK) is an important modulation format for next-generation 40G optical transport systems. It has excellent tolerance against chromatic dispersion, PMD, ...

In Figure 5-9 (b), we have used M = 4, giving four signal points and a system called quadruple phase shift keying (QPSK) or 4PSK . In Figure 5-9 (c) M = 8, i.e. the signal constellation 8PSK , etc.

The versatile shift-keying generator presented in this design idea is built using current-feedback amplifiers (CFAs). The design is centered around a quadrature oscillator. A number of digitally ...