High-speed electrical backplane transmission using duobinary signaling

Abstract

Abstract-High-speed electrical data transmission through lowcost backplanes is a particularly challenging problem. We present for the first time a very effective approach that uses the concept of duobinary signaling to accomplish this task. Using a finite-impulseresponse filter, we are able to compensate for the phase and amplitude response of the backplane such that the resulting frequency response of the channel is that of an ideal duobinary filter. At the output of the backplane, we use an innovative pseudodigital circuit to convert the electrical duobinary to binary. For 10-Gb/s data transmission, we demonstrate a bit error rate 10 13 through electrical backplane traces up to 34 in in length on FR4. A full discussion of the concept, system architecture, and measured results are presented. Analysis is presented that compares and contrasts this approach to PAM-4 and standard nonreturn-to-zero signaling.

Adaptive Transmit-Side Equalization for Serial Electrical Interconnects at 100 Gb/s Using Duobinary

“…The considered architecture uses DB signaling which provides bandwidth reduction (compared to NRZ) and simplicity in decoding (compared to PAM4) [13]. Duobinary was first introduced in [14] and is a form of partial response signaling [15], [16].…”

“…Hence, when the overall channel response has this filter characteristic, an NRZ signal at the input will be transformed into a 3-level DB signal. Furthermore, part of the actual channel loss can be used to form this filter and only a part needs to be compensated by the equalizer [13]. A typical DB eye-diagram is shown in Fig.…”

Design and Comparison of Three 20-Gb/s Backplane Transceivers for Duobinary, PAM4, and NRZ Data

“…With a pulse response shown in Fig. 8(a), 3 the coefficients are readily available by solving the following equations: Fig. 8(b) and (c) summarize the optimal coefficients at 20 Gb/s data rate as a function of channel length for Rogers and FR4 boards.…”

A 10-Gb/s backplane transmitter with a FIR pre-emphasis equalizer to suppress ISI at data centers and edges simultaneously

“…Duobinary signaling has the effect of edge equalization and it generally requires less high frequency boost than data center oriented equalization. Therefore, it has been intensively studied in some recent research papers [3]. Although edge equalizers suppress ISI at transition edges, they leave a significant amount of ISI at data centers.…”