Analysis of issues in gate recess etching in the InAlAs/InGaAs HEMT manufacturing process

Byoung-Gue Min,Jong-Min Lee,Hyung Sup Yoon,Woo-Jin Chang,Jong-Yul Park,Dong Min Kang,Sung-Jae Chang,Hyun-Wook Jung Electronics and Telecommunications Research Instit 2023 ETRI Journal Vol.45 No.1

We have developed an InAlAs/InGaAs metamorphic high electron mobility transistor device fabrication process where the gate length can be tuned within the range of 0.13㎛-0.16㎛ to suit the intended application. The core processes are a two-step electron-beam lithography process using a three-layer resist and gate recess etching process using citric acid. An electron-beam lithography process was developed to fabricate a T-shaped gate electrode with a fine gate foot and a relatively large gate head. This was realized through the use of three-layered resist and two-step electron beam exposure and development. Citric acid-based gate recess etching is a wet etching, so it is very important to secure etching uniformity and process reproducibility. The device layout was designed by considering the electrochemical reaction involved in recess etching, and a reproducible gate recess etching process was developed by finding optimized etching conditions. Using the developed gate electrode process technology, we were able to successfully manufacture various monolithic microwave integrated circuits, including low noise amplifiers that can be used in the 28 GHz to 94 GHz frequency range.

Ontology-lexicon-based question answering over linked data

Jabalameli, Mehdi,Nematbakhsh, Mohammadali,Zaeri, Ahmad Electronics and Telecommunications Research Instit 2020 ETRI Journal Vol.42 No.2

Recently, Linked Open Data has become a large set of knowledge bases. Therefore, the need to query Linked Data using question answering (QA) techniques has attracted the attention of many researchers. A QA system translates natural language questions into structured queries, such as SPARQL queries, to be executed over Linked Data. The two main challenges in such systems are lexical and semantic gaps. A lexical gap refers to the difference between the vocabularies used in an input question and those used in the knowledge base. A semantic gap refers to the difference between expressed information needs and the representation of the knowledge base. In this paper, we present a novel method using an ontology lexicon and dependency parse trees to overcome lexical and semantic gaps. The proposed technique is evaluated on the QALD-5 benchmark and exhibits promising results.

Disputes over the Intellectual Property Rights of Telecommunications Standardization

Park, Ki-Shik,Kim, Young-Tae,Sohn, Hong Electronics and Telecommunications Research Instit 1998 ETRI Journal Vol.20 No.1

Both telecommunications standardization activities and an intellectual property rights (IPRs) system are regarded as effective mechanisms for improving social benefits. Because of inherent conflicts that exist between the two, however, serious problems are generated in the international arena where the competition for technology development and markets is becoming increasingly fierce. In this paper, ways of harmonizing the relationship between the two are explored and explained. For this purpose, telecommunications standardization and IPRs protection mechanisms are described, and their positive and negative effects as well as their inter-relationship are also analyzed. In addition, IPR case studies related to international standardization are explained and analyzed. The Current status and problems of IPRs policy of major international standardization organizations are analyzed as well. Finally, based on the results of the analyses, viable policy recommendations and research strategies for more comprehensive study of the above problems are proposed.

Phase Noise Reduction of Microwave HEMT Oscillators Using a Dielectric Resonator Coupled by a High Impedance Inverter

Lee, Moon-Que,Ryu, Keun-Kwan,Yom, In-Bok Electronics and Telecommunications Research Instit 2001 ETRI Journal Vol.23 No.4

The phase noise reduction in a configuration of the HEMT oscillator with a dielectric resonator coupled by a quarter-wavelength impedance inverter is investigated. Two HEMT oscillators for a satellite payload system are manufactured in the same configuration except for the coupling configuration of the dielectric resonator (DR) in order to empirically demonstrate the phase noise reduction. Experimental result shows that a phase noise reduction by 14 dB can be enhanced by increasing the characteristic impedance of a coupling microstrip impedance inverter.

Power analysis attack resilient block cipher implementation based on 1-of-4 data encoding

Shanmugham, Shanthi Rekha,Paramasivam, Saravanan Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.4

Side-channel attacks pose an inevitable challenge to the implementation of cryptographic algorithms, and it is important to mitigate them. This work identifies a novel data encoding technique based on 1-of-4 codes to resist differential power analysis attacks, which is the most investigated category of side-channel attacks. The four code words of the 1-of-4 codes, namely (0001, 0010, 1000, and 0100), are split into two sets: set-0 and set-1. Using a select signal, the data processed in hardware is switched between the two encoding sets alternately such that the Hamming weight and Hamming distance are equalized. As a case study, the proposed technique is validated for the NIST standard AES-128 cipher. The proposed technique resists differential power analysis performed using statistical methods, namely correlation, mutual information, difference of means, and Welch's t-test based on the Hamming weight and distance models. The experimental results show that the proposed countermeasure has an area overhead of 2.3× with no performance degradation comparatively.

An Advanced Correlation Algorithm between GTEM and OATS for Radiated Emission Tests

Lee, Ae-Kyoung Electronics and Telecommunications Research Instit 1995 ETRI Journal Vol.17 No.3

This paper proposes an algorithm to improve the correlation between giga-hertz transverse electromagnetic (GTEM) cell and open area test site (OATS). It is based on the dipole modeling process of an unknown source object in a GTEM cell and on the evaluation of the approximate far field equations correlated with measured GTEM powers at output port of the GTEM cell. In this algorithm, the relative phase differences between dipole moments play an important part in modeling the test object as a set of dipoles and offer stable calculation of emission values. The radiated emission test using this algorithm requires fifteen orientations of equipment under test, but the increased orientations as compared with the previous method have little effect on the time needed for testing. Radiation from a notebook computer has been tested for statistical analysis of the correlation between GTEM data and OATS data. The emission test results of the notebook computer show that the mean, the standard deviation, and the correlation coefficient are -0.62, 1.99, and +0.85, respectively. These figures indicate that this algorithm provides improved accuracy in the measurement of electromagnetic emissions over the previous method.

Collision-free local planner for unknown subterranean navigation

Jung, Sunggoo,Lee, Hanseob,Shim, David Hyunchul,Agha-mohammadi, Ali-akbar Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.4

When operating in confined spaces or near obstacles, collision-free path planning is an essential requirement for autonomous exploration in unknown environments. This study presents an autonomous exploration technique using a carefully designed collision-free local planner. Using LiDAR range measurements, a local end-point selection method is designed, and the path is generated from the current position to the selected end-point. The generated path showed the consistent collision-free path in real-time by adopting the Euclidean signed distance field-based grid-search method. The results consistently demonstrated the safety and reliability of the proposed path-planning method. Real-world experiments are conducted in three different mines, demonstrating successful autonomous exploration flights in environment with various structural conditions. The results showed the high capability of the proposed flight autonomy framework for lightweight aerial robot systems. In addition, our drone performed an autonomous mission in the tunnel circuit competition (Phase 1) of the DARPA Subterranean Challenge.

Supervised-learning-based algorithm for color image compression

Liu, Xue-Dong,Wang, Meng-Yue,Sa, Ji-Ming Electronics and Telecommunications Research Instit 2020 ETRI Journal Vol.42 No.2

A correlation exists between luminance samples and chrominance samples of a color image. It is beneficial to exploit such interchannel redundancy for color image compression. We propose an algorithm that predicts chrominance components Cb and Cr from the luminance component Y. The prediction model is trained by supervised learning with Laplacian-regularized least squares to minimize the total prediction error. Kernel principal component analysis mapping, which reduces computational complexity, is implemented on the same point set at both the encoder and decoder to ensure that predictions are identical at both the ends without signaling extra location information. In addition, chrominance subsampling and entropy coding for model parameters are adopted to further reduce the bit rate. Finally, luminance information and model parameters are stored for image reconstruction. Experimental results show the performance superiority of the proposed algorithm over its predecessor and JPEG, and even over JPEG-XR. The compensation version with the chrominance difference of the proposed algorithm performs close to and even better than JPEG2000 in some cases.

Adaptive block tree structure for video coding

Baek, Aram,Gwon, Daehyeok,Son, Sohee,Lee, Jinho,Kang, Jung-Won,Kim, Hui Yong,Choi, Haechul Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.2

The Joint Video Exploration Team (JVET) has studied future video coding (FVC) technologies with a potential compression capacity that significantly exceeds that of the high-efficiency video coding (HEVC) standard. The joint exploration test model (JEM), a common platform for the exploration of FVC technologies in the JVET, employs quadtree plus binary tree block partitioning, which enhances the flexibility of coding unit partitioning. Despite significant improvement in coding efficiency for chrominance achieved by separating luminance and chrominance tree structures in I slices, this approach has intrinsic drawbacks that result in the redundancy of block partitioning data. In this paper, an adaptive tree structure correlating luminance and chrominance of single and dual trees is presented. Our proposed method resulted in an average reduction of -0.24% in the Y Bjontegaard Delta rate relative to the intracoding of JEM 6.0 common test conditions.

A low-cost compensated approximate multiplier for Bfloat16 data processing on convolutional neural network inference

Kim, HyunJin Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.4

This paper presents a low-cost two-stage approximate multiplier for bfloat16 (brain floating-point) data processing. For cost-efficient approximate multiplication, the first stage implements Mitchell's algorithm that performs the approximate multiplication using only two adders. The second stage adopts the exact multiplication to compensate for the error from the first stage by multiplying error terms and adding its truncated result to the final output. In our design, the low-cost multiplications in both stages can reduce hardware costs significantly and provide low relative errors by compensating for the error from the first stage. We apply our approximate multiplier to the convolutional neural network (CNN) inferences, which shows small accuracy drops with well-known pre-trained models for the ImageNet database. Therefore, our design allows low-cost CNN inference systems with high test accuracy.