[1]. Yuxiang Zheng and J. Liu, "A 5Gb/s Automatic Within-Pair Skew Compensator for Differential Data in 0.13µm CMOS," IEEE Transactions on Circuits and Systems I, Volume: 58 , Issue: 6 , pp. 1191 - 1202 (Journal)

Abstract-This paper presents an automatic within-pair skew compensator for high-speed differential data transmission. A wide-bandwidth data delay line is proposed to provide adjustable delay for data signals. Also presented is an on-chip within-pair skew detection circuit to detect skew between the differential data signals for automatic close-loop skew compensation. A within-pair skew compensator prototype for 5 Gb/s data was fabricated in 0.13um CMOS. Measurement results show that the within-pair skew compensator can automatically compensate for within-pair skew of 200 ps ( 1 unit interval). It consumes 20.4 mW from 1.2 V supply and occupies 0.015 mm² die area.

Index Terms-Intra-pair skew compensation, skew detection, within-pair skew compensation.

[2]. Yuxiang Zheng, J. Liu, R. Payne, M. Morgan, and H. Lee, "A 5Gb/s Automatic Sub-Bit Between-Pair Skew Compensator for Parallel Data Communications in 0.13μm CMOS," in Digest of Symposium on VLSI Circuits, Jun. 2010, pp. 71-72. (Conference Lecture)

Abstract-A between-pair skew compensator for parallel data communications is presented. It can detect time skew between two independent data sequences using continuous-time correlations and then automatically align the two using a voltage controlled wide-bandwidth data delay line. A 5Gb/s sub-bit between-pair skew compensator in 0.13um CMOS occupies 0.03mm² active die area and dissipates 22.5mW.

[3]. Yuxiang. Zheng, J. Li, J. Liu, and Q. Yu, "Automatic Within-Pair-Skew Compensation for 6.25Gbps Differential Links Using Wide-Bandwidth Delay Units," in Proc. IEEE International Symposium on Circuits and Systems, May 2006, pp. 2121-2124. (Conference Lecture)

Abstract-This paper presents an automatic on-chip skew compensation scheme for within-pair-skew (WPS) in differential high-speed links. The skew compensation is achieved by cascading a series of wide-bandwidth delay cells to obtain constant group delay over the signal bandwidth. A continuous-time correlation circuit with current-mode logic XOR gate followed by a RC low-pass filter is proposed for skew detection. The effects of WPS and the proposed skew compensation scheme have been studied for various time skew and channel attenuation values. Simulation results show that the proposed skew compensation circuits can successfully restore the signal quality close to the condition without WPS, even when the signal with WPS has completely closed eyes.