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A power-scalable 2 Byte I/O operating at 12 Gb/s per lane is reported. The source-synchronous I/O includes controllable TX driver amplitude, flexible RX equalization, and multiple deskew modes. This allows power reduction when operating over low-loss, low-skew interconnects, while at the same time supporting higher-loss channels without loss of bandwidth. Transceiver circuit innovations are described including a low-skew transmission-line clock distribution, a 4:1 serializer with quadrature quarter-rate clocks, and a phase rotator based on current-integrating phase interpolators. Measurements of a test chip fabricated in 32 nm SOI CMOS technology demonstrate 1.4 pJ/b efficiency over 0.75” Megtron-6 PCB traces, and 1.9 pJ/b efficiency over 20” Megtron-6 PCB traces. [ABSTRACT FROM PUBLISHER]

This paper presents a 28-Gb/s transceiver in 32-nm SOI CMOS technology for chip-to-chip communications over high-loss electrical channels such as backplanes. The equalization needed for such applications is provided by a 4-tap baud-spaced feed-forward equalizer (FFE) in the transmitter and a two-stage peaking amplifier and 15-tap decision-feedback equalizer (DFE) in the receiver. The transmitter employs a source-series terminated (SST) driver topology which doubles the speed of existing half-rate designs. The high-frequency boost provided by the peaking amplifier is enhanced by adopting a structure with capacitively coupled parallel input stages and active feedback. A capacitive level-shifting technique is introduced in the half-rate DFE which allows a single current-integrating summer to drive the four parallel paths used for speculating the first two DFE taps. Error-free signaling at 28 Gb/s is demonstrated with the transceiver over a channel with 35 dB loss at half-baud frequency. In a four-port core configuration, the power consumption at 28~Gb/s is 693 mW/lane. [ABSTRACT FROM PUBLISHER]

A source synchronous I/O system based on high-density silicon carrier interconnects is introduced. Benefiting from the advantages of advanced silicon packaging technologies, the system uses 50 \mum-pitch \muC4s to reduce I/O cell size and fine-pitch interconnects on silicon carrier to achieve record-breaking interconnect density. An I/O architecture is introduced with link redundancy such that any link can be taken out of service for periodic recalibration without interrupting data transmission. A timing recovery system using two phase rotators shared across all bits in a receive bus is presented. To demonstrate these concepts, an I/O chipset using this architecture is fabricated in 45 nm SOI CMOS technology. It includes compact DFE-IIR equalization in the receiver, as well as a new all-CMOS phase rotator. The chipset is mounted to a silicon carrier tile via Pb-free SnAg \muC4 solder bumps. Chip-to-chip communication is achieved over ultra-dense interconnects with pitches of between 8 \mum and 22 \mum. 8\,\times\,10-Gb/s data is received over distances up to 4 cm with a link energy efficiency of 5.3 pJ/bit from 1 V TX and RX power supplies. 8\,\times\,9-Gb/s data is recovered from a 6-cm link with 16.3 dB loss at 4.5 GHz with an efficiency of 6.1 pJ/bit. [ABSTRACT FROM PUBLISHER]