The increasing reliance on third-party intellectual property (IP) cores in modern integrated circuit (IC) design has introduced significant security vulnerabilities, particularly the risk of Hardware Trojans (HTs). These malicious modifications can compromise system integrity, leading to data leakage, unauthorized access, or functional failures. Traditional detection methods often depend on the availability of a golden chip, which is not always feasible. This paper presents the 2025 ICCAD CAD Contest Problem A, which challenges participants to develop machine learning-based solutions for detecting HTs directly from gate-level netlists without requiring a golden reference. The problem is formulated with defined Trojan behaviors, input/output specifications, and evaluation metrics, including correctness and F1 score. The contest aims to foster innovation in HT detection by leveraging advanced data-driven techniques and scalable analysis frameworks.

Traditionally, logic synthesis/optimization metric would be majorly determined by PPA (power, performance, area). However, as the technology node shrinks and the design process becomes extremely complicated, iterative optimization flow and local re-synthesis might be invoked to optimize for more variant purposes. It is necessary to have a methodology which is not just a simple cost-function-based algorithm but also can optimize and legalize a design according to a more complex cost estimator.

Boolean Matching problem determines whether two Boolean functions are functionally equivalent under the permutation and negation of inputs and outputs. Prior contest [1] has extended the problem to allow inputs binding with constant value and the ports matching can be one-to-many projection. In this contest, we further extended the problem to consider the ports grouping information, which is caused by the buses or datapaths in the modern digital IC design.

Extracting circuit functionality from a gate-level netlist is critical in CAD tools. For security, it helps designers to detect hardware Trojans or malicious design changes in the netlist with third-party resources such as fabrication services and soft/hard IP cores. For verification, it can reduce the complexity and effort of keeping design information in aggressive optimization strategies adopted by synthesis tools. For Engineering Change Order (ECO), it can keep the designer from locating the ECO gate in a sea of bit-level gates.

Functional ECO is an essential solution in the VLSI design flow. The technique is to realize the functional changes with a minimal patch netlist in the gate-level netlist. As the increasing of the design complexity, functional ECO becomes more and more difficult to generate a minimal patch. ICCAD 2021 CAD contest calls for a feasible and efficient ECO algorithm with behavioral change guidance. More than ordinary functional ECO problems, the RTL designs are provided. Contestants can utilize the behavioral change in RTL designs to minimize the patch for G1.

Device aging, which causes significant loss on circuit performance and lifetime, has been a primary factor in reliability degradation of nanoscale designs. In this article, we propose to take advantage of aging-induced clock skews (i.e., make them useful for aging tolerance) by manipulating and recycling these time-varying skews to compensate for the performance degradation of logic networks. The goal is to assign achievable/reasonable aging-induced clock skews in a circuit, such that its effective performance degradation due to aging can be tolerated. On average, 21.21% aging tolerance can be achieved with insignificant design overhead. Moreover, we employ V th assignment on clock buffers to further tolerate the aging-induced degradation of logic networks. When V th assignment is applied on top of aforementioned aging manipulation, the average aging tolerance can be enhanced to 29.15%.

Concerns exist that the reliability of chips is worsening because of downscaling technology. Among various reliability challenges, device aging is a dominant concern because it degrades circuit performance over time. Traditionally, runtime monitoring approaches are proposed to estimate aging effects. However, such techniques tend to predict and monitor delay degradation status for circuit mitigation measures rather than the health condition of the chip. In this paper, we propose an aging-aware chip health prediction methodology that adapts to workload conditions and process, supply voltage, and temperature variations. Our prediction methodology adopts an innovative on-chip delay monitoring strategy by tracing representative aging-aware delay behavior. The delay behavior is then fed into a machine learning engine to predict the age of the tested chips. Experimental results indicate that our strategy can obtain 97.40% accuracy with 4.14% area overhead on average. To the authors' knowledge, this is the first method that accurately predicts current chip age and provides information regarding future chip health.

Time speculation has been widely used to achieve high performance in modern design as it exploits average-case timing optimization instead of worst-case timing optimization focusing on reducing longest path delay which rarely happens. Variable-latency design (VLD) style is one research category of time speculation. Since process and environmental variations are hard to predict, traditional variable-latency units (VLUs) designed at presilicon stage will suffer significant performance loss due to pessimistic assumptions for addressing variations. In this paper, we propose a novel sensor-based, transition-aware VLU (S-VLU) scheme adapting to process-voltage-temperature (PVT) variations by using in situ sensors to obtain real-time transition information in a circuit. Moreover, we also propose a sensor deployment strategy to achieve near-maximal performance gain. On average, the S-VLU achieves a 31.27% performance improvement as compared to a 19.26% improvement by using traditional HL. The area overhead of the S-VLU is 13.48%. To the best of the authors' knowledge, this is the first wok to address PVT variations in VLD style.

This paper introduces CN-SIM, a cycle accurate, full system, power delivery (PD) noise simulator. CN-SIM provides a cross layer connectivity form application layer, to the architecture layer, to the circuit layer, which is much needed to realistically estimate PD noise. Thus, making it easier for system architects to explore multilayer design optimizations. CN-SIM's granularity at its deepest is at the functional unit (FU) level. The experimental results of running PARSEC suite benchmarks for different system configurations and different industrial PD design have illustrated CN-SIM's capability to capture the crosslayer impact on PD noise.

In advanced technologies, on-chip-variation (OCV) has accounted for a large proportion of clock skew, which limits the performance of a circuit. To mitigate the OCV problem, a mesh structure has been widely used in high-performance designs. Unfortunately, clock mesh structure also causes large power consumption and large power-ground surge current. Therefore, recently, several approaches have been proposed to apply resonant clock to reduce power consumption. However, previous works often suffer from area overhead because of the need to insert large decoupling capacitors. In this paper, we propose a novel resonant clock mesh structure, called ping-pong mesh, to overcome these drawbacks. Our ping-pong mesh contains two submeshes, each of which plays the role of the decoupling capacitor of the other, and the clocks in two submeshes operate in completely opposite phases. Our ping-pong mesh has the following two advantages: 1) a ping-pong mesh does not need additional decoupling capacitors as in previous works and 2) a ping-pong mesh can reduce the power-ground surge current about half of previous works. Benchmark data consistently show that our ping-pong mesh does work well in practice.

In a multipower-mode design, as the range of the supply voltage becomes wide, a large clock skew may occur among different power domains. To remove this clock skew, conventional power-mode-aware buffers (PMABs) require a large overhead on power consumption. In this brief, we propose a new PMAB architecture for wide-voltage-range multipower-mode designs. The proposed PMAB architecture is composed of two serially connected sub-PMABs at two different voltage levels, respectively. In the front sub-PMAB, the low voltage level is used for coarse-grained clock skew minimization. In the back sub-PMAB, the high voltage level is used for fine-grained clock skew minimization. Benchmark data show that the proposed approach can effectively eliminate the clock skew with small power consumption.

As the supply voltage is down to the ultra-low voltage (ULV) level, timing closure becomes a serious challenge in the use of multiple power modes. Due to a wide voltage range, a very huge clock skew may occur among different power modes. To reduce this huge clock skew, the conventional power-mode-aware clock tree often suffers from a huge overhead on power consumption. Moreover, at the ULV level, since the setup time and the hold time of each register dramatically increase, the number of timing violations also increases greatly. However, the existing minimum padding technique cannot fix hold time violations in multiple power modes. Based on those two observations, in this paper, we propose a low-power timing closure methodology, which incorporates the synthesis of clock tree and data path, for multipower-mode ULV designs. Our low-power timing closure methodology has two main approaches. First, we use multiple power modes to build a power-mode-aware clock tree for reducing clock skew with very small power consumption. Second, we propose the first multi-power-mode minimum padding technique to fix all the hold time violations in all the power modes simultaneously. Experimental results consistently show that the integration of both approaches yields the best results.

Preconditioned Conjugate Gradient (PCG) method has been demonstrated to be effective in solving large-scale linear systems for sparse and symmetric positive definite matrices. One critical problem in PCG is to design a good preconditioner, which can significantly reduce the runtime while keeping memory usage efficient. Universal preconditioners are simple and easy to construct, but their effectiveness is highly problem-dependent. On the other hand, domain-specific preconditioners that explore the underlying physical meaning of the matrices usually work better, but are difficult to design. In this paper, we study the problem in the context of power grid simulation, and develop a novel preconditioner based on the power grid structure through simple circuit simulations. Experimental results show 43% reduction in the number of iterations and 23% speedup over existing universal preconditioners.

To conserve energy, a design which utilizes different power modes has been widely adopted. However, when a design has many different power modes, clock tree optimization (CTO) becomes very difficult. In this paper, we propose a two-level power-mode-aware CTO methodology. Among all different power modes, the chip-level CTO globally reduces clock skew among modules, whereas the module-level CTO reduces clock skew within a single module. Our experimental results show that the power-mode-aware CTO can achieve significant improvement in the worst-case condition with only a minor penalty in area.