Parallel Prefix Network Based DQPSK Precoder for High-Speed Optical Transmission

This paper introduced the principle of parallel prefix network (PPN) and proved the feasibility of applying PPN to differential quadrature phase-shift keying (DQPSK) precoder. Kogge Stone (KS) adder is a typical parallel algorithm of PPN. A ameliorated KS adder was proposed to implement the precoder. With 78Mb/s and 128 parallel channels, 20Gb/s DQPSK precoder was achieved in ML523 (Xilinx Virtex V FPGA). Results presented that the clock minimum period was 1.154 ns and the maximum frequency was 866.551 MHz. About 2% of slice logic resource was employed in the implementation.