A 40 nm 16 Gb/s differential transmitter with far-end crosstalk cancellation using injection timing control for high-density flexible flat cables

Abstract

In some long-reach high-density wires such as flexible flat cables, the crosstalk signal from the aggressor to the victim lanes exhibits the time shift that depends on the cables. This paper proposes a far-end crosstalk (FEXT) cancellation method with controllable injection timing of the crosstalk cancellation (XTC) signals into the victim lanes. The proposed method uses a delay-line-based digital-to-time converter for delay tuning and generates the XTC signals at the transmitter, then inject it to cancel the FEXT effectively on these cables. The proposed XTC circuit is implemented in the differential transmitter so that the XTC signal is generated from the digital data signal from the aggressor. The transmitter circuit with the proposed XTC technique is designed in a 40 nm bulk CMOS process, and its feasibility is verified through the post-layout simulation at a data rate of 16 Gb/s.