Design and Feasibility of Multi-Gb/s Quasi-Serial Vertical Interconnects based on TSVs for 3D ICs

This paper proposes a novel technique to exploit the high bandwidth offered by through silicon vias (TSVs). In the proposed approach, synchronous parallel 3D links are replaced by serialized links to save silicon area and increase yield. Detailed analysis conducted in 90 nm CMOS technology shows that the proposed 2-Gb/s/pin quasi-serial link requires approximately five times less area than its parallel bus equivalent at same data rate for a TSV diameter of 20 um

Low Power 3D Serial TSV Link for High Bandwidth Cross-Chip Communication

3D-ICs based on TSV technology provide high bandwidth inter-chip connections. The drawback is that most of the existing TSVs consume a large amount of silicon real estate. We present circuit-level design and analysis of area efficient, low power, high-data-rate 3D serial TSV links. A design space exploration is performed and trade-offs in terms of area, power and performance are presented. Circuit simulations of RC-extracted layouts in 40nm CMOS-technology reveals that 8:1 serialization efficiently balances area consumption and energy efficiency. Using 10μm-diameter TSV technology, an 8Gb/s serial link consumes only 84fJ/bit with 10X area reduction over 8b parallel bus

A Parallelized Layered QC-LDPC Decoder for IEEE 802.11ad

We present a doubly parallelized layered quasi-cyclic low density parity-check decoder for the emerging IEEE 802.11ad multigigabit wireless standard. The decoding algorithm is equivalent to a nonparallelized layered decoder and, thus, retains its favorable convergence characteristics, which are known to be superior to those of flooding schedule based decoders. The proposed architecture was synthesized using a TSMC 40 nm CMOS technology, resulting in a cell area of 0.18 mm2 and a clock frequency of 850 MHz. At this clock frequency, the decoder achieves a coded throughput of 3.12 Gbps, thus meeting the throughput requirements when using both the mandatory BPSK modulation and the optional QPSK modulation

Design and Testing Strategies for Modular 3-D-Multiprocessor Systems Using Die-Level Through Silicon Via Technology

An innovative modular 3-D stacked multi-processor architecture is presented. The platform is composed of completely identical stacked dies connected together by through-silicon-vias (TSVs). Each die features four 32-bit embedded processors and associated memory modules, interconnected by a 3-D network-on-chip (NoC), which can route packets in the vertical direction. Superimposing identical planar dies minimizes design effort and manufacturing costs, ensuring at the same time high flexibility and reconfigurability. A single die can be used either as a fully testable standalone chip multi-processor (CMP), or integrated in a 3-D stack, increasing the overall core count and consequently the system performance. To demonstrate the feasibility of this architecture, fully functional samples have been fabricated using a conventional UMC 90 nm complementary metal–oxide–semiconductor process and stacked using an in-house, via-last Cu-TSV process. Initial results show that the proposed 3-D-CMP is capable of operating at a target frequency of 400 MHz, supporting a vertical data bandwidth of 3.2 Gb/s

Heterogeneous integration of ReRAM crossbars in a CMOS foundry chip

In this paper, we present a heterogeneous integration of ReRAMs with standard CMOS technology by post-processing the Back-End-of-the-Line (BEOL) of fully finished CMOS chips

An Eight lanes 7Gb/s/pin Source Synchronous Single-Ended RX with Equalization and Far-End Crosstalk Cancellation for Backplane Channels

This paper presents a versatile crosstalk cancellation scheme for single-ended multi-lane backplane links. System-level investigations show that a scheme, which combines analog filters and decision-feedback crosstalk compensation on the receiver (RX) side only, can efficiently remove crosstalk patterns in straight channels as well as boards with reflections due to via stubs. An eight-lane single-ended RX has been manufactured in 32-nm SOI CMOS to validate our findings. A CTLE and eight-tap decision feedback equalizer equalize the channel without transmitter feedforward equalizer. A continuous time crosstalk canceller reduces precursors by nearest neighbors, while the residual postcursors from all aggressors are suppressed by direct feedback 7x8-tap decision-feedback crosstalk canceller (DFXC). Measurements with flip-chip packaged RX show that the RX macro can equalize both a 30-dB insertion loss single-ended channel with 0-dB signal-to-crosstalk at Nyquist and a channel with 28-dB attenuation with the signal-to-crosstalk ratio of 6 dB combined with reflections due to via stubs. The RX operates up to 7 Gb/s/pin with PRBS11 data at bit error rate (BER) <10⁻¹², and occupies 300x350 μm² with an energy efficiency of 5.9 mW/Gb/s from 1-V supply

Adaptive optical interconnects: The ADDAPT project

Existing optical networks are driven by dynamic user and application demands but operate statically at their maximum performance. Thus, optical links do not offer much adaptability and are not very energy-effcient. In this paper a novel approach of implementing performance and power adaptivity from system down to optical device, electrical circuit and transistor level is proposed. Depending on the actual data load, the number of activated link paths and individual device parameters like bandwidth, clock rate, modulation format and gain are adapted to enable lowering the components supply power. This enables exible energy-efficient optical transmission links which pave the way for massive reductions of CO2 emission and operating costs in data center and high performance computing applications. Within the FP7 research project Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) dynamic high-speed energy-efficent transceiver subsystems are developed for short-range optical interconnects taking up new adaptive technologies and methods. The research of eight partners from industry, research and education spanning seven European countries includes the investigation of several adaptive control types and algorithms, the development of a full transceiver system, the design and fabrication of optical components and integrated circuits as well as the development of high-speed, low-loss packaging solutions. This paper describes and discusses the idea of ADDAPT and provides an overview about the latest research results in this field

A 5.9mW/Gb/s 7Gb/s/pin 8-Lane Single-Ended RX with Crosstalk Cancellation Scheme using a XCTLE and 56-tap XDFE in 32nm SOI CMOS

This work reports an 8-lane single-ended RX featuring compact and low power far-end crosstalk (FEXT) cancellation circuits. The RX data-path consists of a cross continuous-time linear equalizer (XCTLE) to remove FEXT by nearest aggressors within the channel bundle. Residual post-cursor FEXT is suppressed by a direct feedback 7x8-tap cross decision feedback equalizer (XDFE). A CTLE and 8-tap DFE equalize single-ended channels with 28dB insertion loss at Nyquist frequency without TX FFE. The circuit, fabricated in 32nm SOI CMOS, was measured to receive 7Gb/s/pin PRBS11 data at BER< 10^-12 with 12.5%UI margin. It occupies 300x350um2 with an energy efficiency of 5.9mW/Gb/s

Towards Cost Effective Multi-Core Processor Platforms Using 3-D Stacking Technology

A novel modular, cost e ffective 3D multi-processor architecture is presented. Auto-configurable and independently testable identical dies are stacked exploiting Through-Silicon-Vias (TSV) technology, allowing to target different market segments by selecting the appropriate number of layers. For the purpose of evaluation, dies have been fabricated using a commodity UMC 90nm CMOS process and stacked using a in-house, Via-Last copper TSV process. Each die, featuring four cores interconnected by a Network-on-Chip (NoC), has been designed for a maximum operating frequency of 400MHz resulting in 3.2Gbps data bandwidth