A $\mathbf{4\times 9}\; \text{Gb/s}\ \mathbf{1}\;\text{pJ/b}$ Hybrid NRZ/Multi-Tone I/O With Crosstalk and ISI Reduction for Dense Interconnects

A low-power four-channel hybrid NRZ/multi-tone transceiver for multi-drop bus (MDB) memory interfaces is designed and fabricated in 40 nm CMOS technology. The proposed system achieves 1 pJ/bit power efficiency, while communicating over an MDB channel with 45 dB loss at 3 GHz. The multi-tone (MT) nature of the proposed transceiver helps to control the intersymbol interference (ISI) and reduce the far-end crosstalk (FEXT), which results in a very energy-efficient implementation. The core size area is 80 × 60 μm
²
and 130×60 μm
²
for the TX and RX blocks (including the clock unit), respectively.