Design studies for ASIC implementations of 28 GS/s optical QPSK- and 16-QAM-OFDM transceivers.

Area of Science:

• Electrical Engineering
• Optical Communications
• Digital Signal Processing

Background:

• Optical orthogonal frequency division multiplexing (OFDM) is a promising technology for high-speed optical communication systems.
• Digital signal processing (DSP) is crucial for implementing advanced modulation formats like Quadrature Phase Shift Keying (QPSK) and 16-Quadrature Amplitude Modulation (16-QAM) in optical transceivers.

Purpose of the Study:

• To evaluate the suitability of OFDM technology for low-cost optical interconnects.
• To assess the performance, power consumption, and chip area of DSP circuits for QPSK- and 16-QAM-encoded OFDM transceivers.

Main Methods:

• Register-transfer-level (RTL) design of DSP circuits for 21.8 Gb/s and 43.7 Gb/s transceivers.
• Synthesis and simulation of the designed DSP components, including Fast Fourier Transforms (FFTs), equalization, (de)mapping, and clipping/scaling circuits.
• Power consumption analysis based on synthesis results using a 65 nm standard-cell library.

Main Results:

• The DSP components for QPSK-encoded OFDM transceivers consumed 18.2 mW/Gb/s.
• The DSP components for 16-QAM-encoded OFDM transceivers consumed 12.8 mW/Gb/s.
• The study provides a detailed assessment of power consumption and performance metrics for high-speed optical OFDM transceivers.

Conclusions:

• OFDM technology, with its efficient DSP implementation, is suitable for low-cost optical interconnects.
• The designed DSP circuits demonstrate competitive power efficiency for high-speed optical communication.
• Further optimization of DSP components can enhance the feasibility of OFDM for next-generation optical networks.