A 10.3-GS/s, 6-Bit Flash ADC for 10G Ethernet Applications

Increasing demand for bandwidth has resulted in broad adoption of 10G Ethernet throughout the network infrastructure. A wide array of standards has been developed supporting 10GE over both fiber and copper media. A particularly challenging standard is Long Reach Multimode (LRM), which targets installed base multi-mode fiber. The challenging communication channels presented by legacy fibers at the 10.3Gb/s rate lend themselves to the use of DSP-based adaptive receivers. Such receivers can be designed to be quite flexible - at once capable of meeting the performance requirements for multiple 10GE standards for all media: short- and long-reach multi-mode fiber (MMF), 10-to-80km single-mode fiber (SMF), as well as PCB backplanes and copper cable channels. A critical block for such receivers is the frontend ADC that digitizes the incoming data. This paper describes a 40nm CMOS 10.3GS/s, 6b Flash ADC used as the analog frontend for a DSP-based receiver that meets the requirements for all the NRZ 10G Ethernet standards, for both fiber (LRM, SR, LR, ER ZR) and copper channels (KR and CX1) [1].