High-Speed Low-Current Duobinary Signaling Over Active Terminated Chip-to-Chip Interconnect

Abstract

In this work we propose high-speed low-current duobinary signaling scheme over an active terminated chip-to-chip interconnect. The active termination scheme eliminates the need of any dedicated passive terminator both at the transmitter and receiver, avoiding signal reflection. Elimination of the passive terminator helps to reduce the transmitted signal level without effecting signal detect-ability of the receiver and also removes the thermal noise of the terminator. To implement bandwidth efficient duobinary signaling, we present a current-mode high-speed precoder operating at 10-Gb/s. A low-current active terminated driver based on modified Cherry-Hooper topology is proposed. At the receive-end, we propose an active terminated current-mode receiver(Rx) with regulated gate cascode (RGC) based transimpedance amplifier(TIA). Folded active inductor peaking is used to enhance the bandwidth of this TIA. We also propose lowpower broadband equalizer topology for channel equalization. The duobinary transmitter and receiver circuits are implemented in 1.8-V, 0.18-μm Digital CMOS technology with an f_T of 27-GHz. The designed high speed duobinary Tx/Rx circuits work up-to 8-Gb/s speed while transmitting the data over FR4 PCB trace of length 29.5-inch and for the targeted bit-error-rate(BER) of 10^−12. The power consumed in the transmitter and receiver circuits is 42.9-mW at 8-Gb/s