The adoption of HLS has been driven by the need to tackle growing verification costs in traditional RTL design flows. This paper presents an overview of design, optimization and verification using HLS. It also outlines some of the requirements for HLS design to fit into existing design and verification flows and ways in which such flows might be adapted as HLS is more widely deployed.

Aging effects (such as Negative Bias Temperature Instability (NBTI)) can cause the temporal degradation of threshold voltage of transistors, and have become major reliability concerns for deep-submicron (DSM) designs. Meanwhile, leakage power dissipation becomes dominant in total power as technology scales. While multi-threshold voltage assignment has been shown as an effective way to reduce leakage, the NBTI-degradation rates vary with different initial threshold voltage assignment, and therefore motivates the co-optimizations of leakage reduction and NBTI mitigation. This paper minimizes leakage power during high-level synthesis of circuits with bounded delay degradation (thus guaranteed lifetime), using multi-Vthresource libraries. We first propose a fast evaluation approach for NBTI-induced degradation of architectural function units, and multi-Vthresource libraries are built with degradation characterized for each function unit. We then propose an aging-bounded high-level synthesis framework, within which the degraded delays are used to guide the synthesis, and leakage power is optimized through the proposed aging-aware resource rebinding algorithm. Experimental results show that, the proposed techniques can effectively reduce the leakage power with an extra 26% leakage reduction, compared to traditional aging-unaware multi-Vthassignment approach.

The ever-increasing chip power dissipation in SoCs has imposed great challenges on today's circuit design. It has been shown that multiple threshold and supply voltages assignment (multi-Vth/Vdd) is an effective way to reduce power dissipation. However, most of the prior multi-Vth/Vddoptimizations are performed under deterministic conditions. With the increasing process variability that has significant impact on both the power dissipation and performance of circuit designs, it is necessary to employ statistical approaches in analysis and optimizations for low power. This paper studies the impact of process variations on the multi-Vth/Vddtechnique at the behavioral synthesis level. A multi-Vth/Vddresource library is characterized for delay and power variations at different voltage combinations. A parametric yield-driven resource binding algorithm is then proposed, which uses the characterized power and delay distributions and efficiently maximizes power yield under a timing yield constraint. During the resource binding process, voltage level converters are inserted between resources when required. Experimental results show that significant power reduction can be achieved with the proposed variation-aware framework, compared with traditional worst-case based deterministic approaches.

As technology scales, the delay uncertainty caused by process variations has become increasingly pronounced in deep submicron designs. In the presence of process variations, worst-case timing analysis may lead to overly conservative synthesis, and may end up using excess resources to guarantee design constraints. In this paper, we propose an efficient variation-aware resource sharing and binding algorithm in behavioral synthesis, which takes into account the performance variations for functional units. The performance yield, which is defined as the probability that the synthesized hardware meets the target performance constraints, is used to evaluate the synthesis result. An efficient metric called statistical performance improvement, is used to guide resource sharing and binding. The proposed algorithm is evaluated within a commercial synthesis framework that generates optimized RTL netlists from behavioral specifications. The effectiveness of the proposed algorithm is demonstrated with a set of industrial benchmark designs, which consist of blocks that are commonly used in wireless and image processing applications. The experimental results show that our method achieves an average 33% area reduction over traditional methods, which are based on the worst-case delay analysis, with an average 10% run time overhead.

This panel discusses power optimization at the system level. What are the needs and opportunities? What are examples of successful practices? Can system-level power optimizations ever be automated? Can power optimizations be the enabling event for a methodology change in system-level design?

The algorithms used in wireless applications are increasingly more sophisticated and consequently more challenging to implement in hardware. Traditional design flows require developing the micro architecture, coding the RTL, and verifying the generated RTL against the original functional C or MATLAB specification. This paper describes a C-based design flow that is well suited for the hardware implementation of DSP algorithms commonly found in wireless applications. The C design low relies on guided synthesis to generate the RTL directly from the untimed C algorithm. The specifics of the C-based design flow are described using a simple DSP filtering algorithm consisting of a forward adaptive equalizer, a 64-QAM slicer and an adaptive decision feedback equalizer. The example illustrates some of the capabilities and advantages offered by this flow.

We present a finite-state model for scheduling constraints in digital system design. We define a two-level hierarchy of finite-state machines: a behavior FSM's input and output events are partially ordered in time; a register-transfer FSM is a traditional FSM whose inputs and outputs are totally ordered in time. Explicit modeling of scheduling constraints is useful for both high-level synthesis and verification-we can explicitly search the space of register-transfer FSM's which implement a desired schedule. State-based models for scheduling are particularly important in the design of control-dominated systems. This paper describes the BFSM I model, describes several important operations and algorithms on BFSM's and networks of communicating BFSM's, and illustrates the use of BFSM's in high-level synthesis.

This paper describes a new algorithm for generation of scheduling constraints in networks of communicating processes. Our model of communication intertwines the schedules of the machines in the network: timing constraints of a machine may affect the schedules of machines communicating with it. This model of communication facilitates the modular specification of timing constraints. A feasible solution to the set of constraints generated gives a schedule for each machine in the network such that all internal constraints of each machine are satisfied and communication between machines is statically coordinated whenever possible. Static scheduling of communication saves on the cost of handshake associated with dynamic synchronization. Our algorithm can handle complex, state-dependent and cyclic timing constraints. Experimental results show that our algorithm is both effective and efficient.>