This paper presents a fast dynamic biasing technique for push-pull input buffers in high-speed ADCs. It introduces a coupling capacitor to the gate of the buffer to pull down its overdrive voltage after sampling, thus turning it off in idle time. Due to the complementary structure, the kickback to the input from the gate of PMOS and NMOS can be canceled out, introducing no perturbation. The proposed technique is implemented and validated in a 28nm CMOS process with a push-pull source follower input buffer which works under a 1.2 V power supply with a bias current of 7.5mA on one side. The dynamic biasing circuit shuts down the single-ended current to 2mA after sampling, reducing the average current by 40% with 50% duty cycle.

This paper proposes a low-noise high-voltage rail-to-rail operational amplifier based on BCD process. For the pro-tection of low-voltage devices in input stage, this paper proposes a common-mode voltage following circuit which not only realizes the stable performance of low-voltage input devices but also improves the gain under full supply voltage. In order to improve the response speed of large signals, this paper proposes a dynamic slew-rate enhancement technology to achieve the characteristics of low quiescent current and large slew-rate. Besides, this paper optimized the low-frequency noise of the proposed architecture. The circuit uses 180nmBCD process, and the simulation results show that after applying the above technology, the supply voltage range is 3.5-36 V, the quiescent current is about 0.99 mA, the equivalent input noise is 0.82 uVp-p, the slew-rate is 15.2 V/us, the setting time is 0.66 us and the open loop gain is 135 dB in full supply voltage range.

In this paper, we focus on the portability issue in profiled side-channel attacks (SCAs) that arises due to significant device-to-device variations. Device discrepancy is inevitable in realistic attacks, but it is often neglected in research works. In this paper, we identify such device variations and take a further step towards leveraging the transferability of neural networks. We propose a novel adversarial learning-based profiled attack (AL-PA), which enables our neural network to learn device-invariant features. We evaluated our strategy on eight XMEGA microcontrollers. Without the need for target-specific preprocessing and multiple profiling devices, our approach has outperformed the state-of-the-art methods.

With the globalization of the manufacturing supply chain, the malicious modification existing in the middle of distrust is becoming an important security issue on the chip. These modifications are called hardware Trojan (HT). HT is difficult to detect due to its high concealment and diversity of implementation. HT detection based on the side channel is a relatively effective detection method because it does not need to trigger the Trojan or destroy the chip. However, detection based on the side channel faces two major challenges. Firstly, the side channel detection is quite dependent on the golden model. The second one relates to the accuracy of the samples. Side channel information of the chip comes from the hardware manufacturing process and implementation, so it is obviously affected by process variation. In the existing work, many self-reference detection methods have been proposed to solve the problem of missing golden models. However, the existing methods often have special requirements for the circuit structure (such as the need for self-similar structures in the circuit). And, they can hardly resist process variation. This paper combines design and detection. We select the power consumption generated at different times and construct two self-reference ‘knapsack’ to detect HT. The solution proposed in this article is a kind of self-reference method, but we need neither self-similar structures nor the same state of some clocks in the circuit. Meanwhile, by constructing the ‘knapsack,’ we reduce the impact of process variation on detection accuracy because the process variation in the two sets of power consumption is balanced.

Duplicates in data streams may often be observed by the projection on a subspace and/or multiple recordings of objects. Without the uniqueness assumption on observed data elements, many conventional aggregates computation problems need to be further investigated due to their duplication-sensitive nature. In this paper, we present novel, space-efficient, one-scan algorithms to continuously maintain duplicate-insensitive order sketches so that rank-based queries can be approximately processed with a relative rank error guarantee \epsilon in the presence of data duplicates. Besides the space efficiency, the proposed algorithms are time-efficient and highly accurate. Moreover, our techniques may be immediately applied to the heavy hitter problem against distinct elements and to the existing fault-tolerant distributed communication techniques. A comprehensive performance study demonstrates that our algorithms can support real-time computation against high-speed data streams.

Skyline computation has many applications including multi-criteria decision making. In this paper, we study the problem of selecting k skyline points so that the number of points, which are dominated by at least one of these k skyline points, is maximized. We first present an efficient dynamic programming based exact algorithm in a 2d-space. Then, we show that the problem is NP-hard when the dimensionality is 3 or more and it can be approximately solved by a polynomial time algorithm with the guaranteed approximation ratio 1-1/e. To speed-up the computation, an efficient, scalable, index-based randomized algorithm is developed by applying the FM probabilistic counting technique. A comprehensive performance evaluation demonstrates that our randomized technique is very efficient, highly accurate, and scalable.

In this paper, we investigated the problem of approximately processing rank queries against distinct data elements in a data stream with the presence of duplicated data elements. Novel space and time efficient techniques are developed for continuously maintaining order statistics so that rank queries can be answered with a relative error guarantee. This is the first work providing the space and time efficient data stream techniques to process approximate rank queries with relative error guarantees against distinct data elements.

Quantile computation has many applications including data mining and financial data analysis. It has been shown that an /spl epsi/-approximate summary can be maintained so that, given a quantile query (/spl phi/,/spl epsi/), the data item at rank /spl lceil//spl phi/N/spl rceil/ may be approximately obtained within the rank error precision /spl epsi/N over all N data items in a data stream or in a sliding window. However, scalable online processing of massive continuous quantile queries with different /spl phi/ and /spl epsi/ poses a new challenge because the summary is continuously updated with new arrivals of data items. In this paper, first we aim to dramatically reduce the number of distinct query results by grouping a set of different queries into a cluster so that they can be processed virtually as a single query while the precision requirements from users can be retained. Second, we aim to minimize the total query processing costs. Efficient algorithms are developed to minimize the total number of times for reprocessing clusters and to produce the minimum number of clusters, respectively. The techniques are extended to maintain near-optimal clustering when queries are registered and removed in an arbitrary fashion against whole data streams or sliding windows. In addition to theoretical analysis, our performance study indicates that the proposed techniques are indeed scalable with respect to the number of input queries as well as the number of items and the item arrival rate in a data stream.

Summarizing topological relations is fundamental to many spatial applications including spatial query optimization. In this article, we present several novel techniques to effectively construct cell density based spatial histograms for range (window) summarizations restricted to the four most important level-two topological relations: contains, contained, overlap, and disjoint. We first present a novel framework to construct a multiscale Euler histogram in 2D space with the guarantee of the exact summarization results for aligned windows in constant time. To minimize the storage space in such a multiscale Euler histogram, an approximate algorithm with the approximate ratio 19/12 is presented, while the problem is shown NP-hard generally. To conform to a limited storage space where a multiscale histogram may be allowed to have only k Euler histograms, an effective algorithm is presented to construct multiscale histograms to achieve high accuracy in approximately summarizing aligned windows. Then, we present a new approximate algorithm to query an Euler histogram that cannot guarantee the exact answers; it runs in constant time. We also investigate the problem of nonaligned windows and the problem of effectively partitioning the data space to support nonaligned window queries. Finally, we extend our techniques to 3D space. Our extensive experiments against both synthetic and real world datasets demonstrate that the approximate multiscale histogram techniques may improve the accuracy of the existing techniques by several orders of magnitude while retaining the cost efficiency, and the exact multiscale histogram technique requires only a storage space linearly proportional to the number of cells for many popular real datasets.

The skyline operator is important for multicriteria decision-making applications. Although many recent studies developed efficient methods to compute skyline objects in a given space, none of them considers skylines in multiple subspaces simultaneously. More importantly, the fundamental problem on the semantics of skylines remains open: Why and in which subspaces is (or is not) an object in the skyline? Practically, users may also be interested in the skylines in any subspaces. Then, what is the relationship between the skylines in the subspaces and those in the super-spaces? How can we effectively analyze the subspace skylines? Can we efficiently compute skylines in various subspaces and answer various analytical queries?In this article, we tackle the problem of multidimensional subspace skyline computation and analysis. We explore skylines in subspaces. First, we propose the concept of Skycube, which consists of skylines of all possible nonempty subspaces of a given full space. Once a Skycube is materialized, any subspace skyline queries can be answered online. However, Skycube cannot fully address the semantic concerns and may contain redundant information. To tackle the problem, we introduce a novel notion of skyline group which essentially is a group of objects that coincide in the skylines of some subspaces. We identify the decisive subspaces that qualify skyline groups in the subspace skylines. The new notions concisely capture the semantics and the structures of skylines in various subspaces. Multidimensional roll-up and drill-down analysis is introduced. We also develop efficient algorithms to compute Skycube, skyline groups and their decisive subspaces. A systematic performance study using both real data sets and synthetic data sets is reported to evaluate our approach.

We consider the problem of efficiently computing the skyline against the most recent N elements in a data stream seen so far. Specifically, we study the n-of-N skyline queries; that is, computing the skyline for the most recent n (/spl forall/n/spl les/N) elements. Firstly, we developed an effective pruning technique to minimize the number of elements to be kept. It can be shown that on average storing only O(log/sup d/ N) elements from the most recent N elements is sufficient to support the precise computation of all n-of-N skyline queries in a d-dimension space if the data distribution on each dimension is independent. Then, a novel encoding scheme is proposed, together with efficient update techniques, for the stored elements, so that computing an n-of-N skyline query in a d-dimension space takes O(log N+s) time that is reduced to O(d log log N+s) if the data distribution is independent, where s is the number of skyline points. Thirdly, a novel trigger based technique is provided to process continuous n-of-N skyline queries with O(/spl delta/) time to update the current result per new data element and O(log s) time to update the trigger list per result change, where /spl delta/ is the number of element changes from the current result to the new result. Finally, we extend our techniques to computing the skyline against an arbitrary window in the most recent N element. Besides theoretical performance guarantees, our extensive experiments demonstrated that the new techniques can support on-line skyline query computation over very rapid data streams.