A Wide-Range Inter-Wire De-Skewing for IL Warping Mitigation in Spatially Correlated Coded Signaling-Based Transceiver

This paper analyzes an effect of inter-wire skew on signal integrity in a multi-channel system and proposes circuit techniques to enhance signal integrity by using a spatially correlated coded signaling (SCCS). Through the in-depth analysis, the paper investigates a relation between skew and insertion loss (IL), and highlights an importance of wide-range inter-wire de-skewing (IWD). The proposed phase interpolator (PI)-based IWD technique adjusts the transition edges of receiver inputs to minimize skew caused by mismatch components, which increases timing jitter. The transceiver employs pseudo-differential signaling to verify the effect of the IWD in SCCS. The transmitter integrates a feed-forward equalizer (FFE) with a latch-based re-timer and a PI for each channel. Additionally, a 3-tap FFE at the transmitter and a continuous-time linear equalizer (CTLE) at the receiver are incorporated to compensate for channel ISI. Fabricated in 40-nm CMOS technology, the proposed 8-channel transceiver achieves an aggregate throughput of 112 Gb/s with a bit error rate (BER) below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{\mathbf {-12}}$</tex-math> </inline-formula>. The transceiver occupies 0.382 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while achieving energy efficiencies of 0.77 pJ/bit/ch for the transmitter and 1.45 pJ/bit/ch for the receiver.