Transmission design technique for 25-Gbps retimer

We developed a long channel backplane 25-Gbps transmission technology for next-generation high-speed I/O applications. To achieve long-channel backplane traces at 25 Gbps, main jitter sources such as ISI, crosstalk, power supply noise, and circuit origin including random jitter need to be drastically reduced. Among these, ISI is the largest jitter source. When multiple equalization devices are used, the distribution method of the quantity of equalization is a problem. We therefore reduce ISI jitter and suggest the most suitable equalization technique to improve transmission margin. Our strategy is to optimize distribution of the quantity of equalization so that jitter is minimized. We were able to realize a small jitter of just 5.5 ps, and design characteristics in good agreement with the measurements were demonstrated by use of the proposed technique.