Energy Efficient Resistor-Transconductor Hybrid-Based Full-Duplex Transceiver for Serial Link

This paper presents an energy-efficient full-duplex simultaneous bidirectional (FD-SBD) signaling transceiver to double the aggregate data transfer per pin for serial links. For achieving FD-SBD signaling, the transceiver employs a resistor-transconductance (R-Gm) hybrid-based subtractor to enable concurrent transmission and reception of non-return to zero (NRZ) data stream on a single differential channel. The transmitter of a conventional current-mode R-Gm hybrid transmits through a split termination, which effectively reduces the impedance at the transmitting node and increases the power consumed by the transmitter by almost two times compared to the conventional current-mode logic (CML) transmitter. In this work, we have proposed a current-sharing topology by reusing the same transmitter current in both transceivers so that the power consumed by the transmitters is reduced by $2\times $ . A prototype of the proposed transceiver has been implemented in 65 nm CMOS technology for full-duplex signaling across a short FR4 link with a 2.5 dB insertion loss at Nyquist frequency. Measured results give an energy efficiency of 1.7 pJ/b at an aggregate data rate of 8.6 Gb/s with a bit error rate (BER) $\lt 10^{-12}$ .