Design Methodologies and Architecture Solutions for High-Performance Interconnects

ABSTRACT In Deep Sub-Micron (DSM) technologies, interconnects play a crucial role in the correct functionality and largely impact the performance of complex System-on-Chip (SoC) designs. For technologies of 0.25µm and below, wiring capacitance dominates gate capacitance, thus rapidly increasing the interconnect-induced delay. Moreover, the coupling capacitance becomes a significant portion of the on-chip total wiring capacitance, and coupling between adjacent wires cannot be considered as a second-order effect any longer. As a consequence, the traditional top-down design methodology is ineffective, since the actual wiring delays can be computed only after layout parasitic extraction, when the physical design is completed. Fixing all the timing violations often requires several time-consuming iterations of logical and physical design, and it is essentially a trial-and-error approach. Increasingly tighter time-to-market requirements dictate that interconnect parasitics must be taken into account during all phases of the design flow, at different level of abstractions. However, given the aggressive technology scaling trends and the growing design complexity, this approach will only temporarily ameliorate the interconnect problem. We believe that in order to achieve gigascale designs in the nanometer regime, a novel design paradigm, based on new forms of regularity and newly created IP (Intellectual Property) blocks must be developed, to provide a direct path from system-level architectural exploration to physical implementation

Physical design and verification for Microscale Modular Assembled ASIC (M2A2) circuits

The overall goal of this project is to bring down the fabrication cost for low volume ASICs by introducing a novel 'pick and place' mechanism for micro-scale elements of ASICs referred to here as feedstock. This new feedstock based ASIC design flow is referred as Microscale Modular Assembled ASIC (M2A2) design flow. This report complements efforts in fabrication and other Electronic Design Automation (EDA) aspects carried out by researchers at The University of Texas at Austin studying this new mechanism for ASIC design and manufacture. For the purpose of this study, the conventional industrial practice in ASIC design flow was analyzed and modifications to that flow were explored. The initial Synthesis solution was developed using Synopsys's Design Compiler (DC) tool. However, due to the limitations of the tool, the final solution was developed based on Cadence tools. The main blocks of the design flow in this report are Synthesis and analysis of its capabilities; Conformal ECO; Post-Mask spare cell mapping; Post-Mask Clock Tree Synthesis (CTS) and Route; Post-Mask timing and Design Rule Violation (DRV) fixing; and Verification. The Standard Cell-based ASIC design was used as a benchmark and it was compared to M2A2 design flowElectrical and Computer Engineerin

EDA design for Microscale Modular Assembled ASIC (M2A2) circuits

As the semiconductor industry has driven down the minimum feature size to well below 50nm, the mask cost to make devices has skyrocketed. The cost for a full set of masks is estimated to be about $1.5M for 90nm node devices and exceeding$2M for 65nm lithography nodes. According to some estimates, mask writing time goes up as a power of five as feature sizes are decreased below 50nm. In addition, higher complexity of large designs increases the number of design re-spins. The above two factors lead to considerable increase in the nonrecurring engineering cost (NRE) for standard cell ASICs, which has become prohibitively expensive for low to mid volume applications. Field programmable gate array (FPGAs) offer an acceptable solution for fast prototyping and ultra-low volume applications, but are generally not seen as a replacement for ASICs because of their highly inefficient space utilization, lower performance/speed and high power consumption. This is particularly the case as mobility has driven expectations for small form factor and low power consumption. In this work, a new type of ASICs named as Microscale Modular Assembled ASIC (M2A2) is proposed. This technology is a novel application of the high-speed, precision assembly technique for fabrication of ASICs using a limited number of mass-produced feedstock logic circuits. The idea is to share the mask cost for sub-100nm feature sizes across a large number of ASIC designs, decreasing the NRE for individual designs. The concept of constructing ASICs using repeating logic elements is based on previous works where it has been shown that ASICs made of via/metal configured structured elements can achieve space utilization and performance comparable to cell based ASICs. However, in the proposed technique, we provide significantly more choice in the transistor layer, in terms of feedstock types and their configuration. This thesis document deals with the electronic design automation (EDA) design for microscale modular assembled ASIC based circuits. The document discusses the design of feedstock cells, generation of feedstock preplaced design, generation of design collaterals to support M2A2 EDA flow, and front end M2A2 synthesis flow to meet the required functionality of design and achieve optimal quality of results (QoR) metrics in terms of circuit performance/speed, power and areaElectrical and Computer Engineerin

An architectural exploration of via patterned gate arrays

In this work we investigate the architecture of a Via Patterned Gate Array (VPGA) [1], focusing primarily on: 1) the optimal lookup table (LUT) size; and 2) a comparison the crossbar and switch block routing architectures. Unlike FPGAs, the routing architectures in a VPGA do not dominate the total area of the circuit. Therefore our results suggest that using smaller LUTs results in a much faster and smaller design. In the routing architecture comparison, our results also show that the switch block architecture is inferior to the crossbar architecture in terms of area utilization. As the number of routing tracks grows, the switch block architecture begins to dominate the total area of the design as in the case of the FPGAs