Memristor Binarized Neural Networks

Khoa Van Pham,Tien Van Nguyen,Son Bao Tran,HyunKyung Nam,Mi Jung Lee,Byung Joon Choi,Son Ngoc Truong,Kyeong-Sik Min 대한전자공학회 2018 Journal of semiconductor technology and science Vol.18 No.5

Binarized Neural Networks (BNNs) use only binary synapses of +1 and -1, not allowing any intermediate weights between -1 and +1. Though the recognition rate of BNNs is lower than the conventional Deep Neural Networks (DNNs), BNNs have attracted many interests nowadays, because BNNs do not need the complicated multiplication such as DNNs. Binary memristor crossbars can be very suitable to realize BNN hardware. This is because, in memristor BNNs, simple binary operation can be performed in bitwise manner for all the columns in memristor crossbars, simultaneously. In this paper, single-column and double-column memristor BNNs are presented, respectively. In addition, ReLU and sigmoid activation function circuits are also proposed with CMOS circuits. The designed Memristor-CMOS hybrid circuits of BNNs have been tested for MNIST vectors. The memristor BNNs could recognize almost 90% MNIST digits when the memristance variation is as large as 25%. For variation tolerance, the memristor BNNs are compared with the multi-valued memristor neural networks such as 4-bit, 6-bit, etc, in this paper. As a result, it has been confirmed the memristor BNNs become more variation-tolerant than the multi-valued memristor NNs when the variation becomes larger than 22%. Comparing the single-column and doublecolumn BNNs in this paper indicates that the singlecolumn BNN can save power consumption and array area almost by half than the double-column. This is because the single-column has just half memristors than the double-column. And, we measured the single-column and double-column BNNs using the fabricated memristor array. In this measurement, both the double-column and single-column BNNs were observed to work well.

Thermoelectric Energy Harvesting Circuit With 60-mV Input Voltage

Khoa Van Pham,Son Ngoc Truong,Wonsun Yang,Kyeong-Sik Min 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.11

A Thermoelectric Energy Harvesting Circuit For a Wearable Application

Khoa Van Pham,Son Ngoc Truong,Wonsun Yang,Kyeong-Sik Min 한국전기전자학회 2017 전기전자학회논문지 Vol.21 No.1

In recent year, energy harvesting technologies from the ambient environments such as light, motion, wireless waves, and temperature again a lot of attraction form research community [1-5] due to its efficient solution in order to substitute for conventional power delivery methods, especially in wearable together with on-body applications. The drawbacks of battery-powered characteristic used in commodity applications lead to self-powered, long-lifetime circuit design. Thermoelectric generator, a solid-state sensor, is useful compared to the harvesting devices in order to enable self-sustained low-power applications. TEG based on the Seebeck effect is utilized to transfer thermal energy which is available with a temperature gradient into useful electrical energy. Depending on the temperature difference between two sides, amount of output power will be proportionally delivered. In this work, we illustrated a low-input voltage energy harvesting circuit applied discontinuous conduction mode (DCM) method for getting an adequate amount of energy from thermoelectric generator (TEG) for a specific wearable application. With a small temperature gradient harvested from human skin, the input voltage from the transducer is as low as 60mV, the proposed circuit, fabricated in a 0.6㎛ CMOS process, is capable of generating a regulated output voltage of 4.2V with an output power reaching to 40㎛W. The proposed circuit is useful for powering energy to battery-less systems, such as wearable application devices.

A Thermoelectric Energy Harvesting Circuit For a Wearable Application

Pham, Khoa Van,Truong, Son Ngoc,Yang, Wonsun,Min, Kyeong-Sik Institute of Korean Electrical and Electronics Eng 2017 전기전자학회논문지 Vol.21 No.1

In recent year, energy harvesting technologies from the ambient environments such as light, motion, wireless waves, and temperature again a lot of attraction form research community [1-5] due to its efficient solution in order to substitute for conventional power delivery methods, especially in wearable together with on-body applications. The drawbacks of battery-powered characteristic used in commodity applications lead to self-powered, long-lifetime circuit design. Thermoelectric generator, a solid-state sensor, is useful compared to the harvesting devices in order to enable self-sustained low-power applications. TEG based on the Seebeck effect is utilized to transfer thermal energy which is available with a temperature gradient into useful electrical energy. Depending on the temperature difference between two sides, amount of output power will be proportionally delivered. In this work, we illustrated a low-input voltage energy harvesting circuit applied discontinuous conduction mode (DCM) method for getting an adequate amount of energy from thermoelectric generator (TEG) for a specific wearable application. With a small temperature gradient harvested from human skin, the input voltage from the transducer is as low as 60mV, the proposed circuit, fabricated in a $0.6{\mu}m$ CMOS process, is capable of generating a regulated output voltage of 4.2V with an output power reaching to $40{\mu}W$. The proposed circuit is useful for powering energy to battery-less systems, such as wearable application devices.

Defect-Tolerant Training of Neuromorphic Memristor Crossbars

Khoa Van Pham,Tien Van Nguyen,Kyeong-Sik Min 대한전자공학회 2019 대한전자공학회 학술대회 Vol.2019 No.6

Hybrid Pulse-width Modulation Strategy with Reduced CMV Frequency and Improved Switching Loss for Three-Level NPC Converters

Khoa Dang Pham,Nho-Van Nguyen 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

High-frequency Common-mode voltage (CMV) excites undesirable bearing current and motor ground leakage current due to capacitive nature of Common-mode (CM) impedance. This high-frequency CMV can be effectively eliminated with Zero-CMV Pulse-width modulation (ZCMV-PWM) schemes at the expense of inferior output harmonic distortion and high switching loss. Hence, a PWM strategy with reduced CMV magnitudes, zero average CMV, and improved output harmonic distortion, namely RCMV1, offers an attractive solution to reduce adverse effects of CMV. However, the CMV frequency of which or the number of variations in CMV values is 6 times per carrier period. Hence, to inherit improved harmonic distortion offered by this scheme while bridging the gap of CMV frequency with respect to ZCMV-PWM schemes, the switching patterns in RCMV1 are modified to reduce CMV frequency. The resulting switching sequences, namely MRCMV1 suffers high switching loss akin to ZCMV-PWM schemes. As a result, two other types of sequences, namely MRCMV2 and M-RCMV3 are used along with M-RCMV1 with the information of three-phase currents to minimize switching loss, hence the term hybrid PWM or HRCMVSLO. In comparison to previously proposed schemes, i.e., ZCMV-PWM with improved switching loss (ZCMV-SLO) and ZCMV-PWM with enhanced output harmonic distortion (ZCMV-THD), HRCMV-SLO produces better output harmonic distortion while achieving comparable and lower switching loss as opposed to ZCMV-SLO and ZCMV-THD respectively. These improvements come with the loss of higher RMS value of leakage current. Simulation and experimental results substantiate the effectiveness of HRCMV-SLO.

Pulse-Width Modulation Strategy for Common Mode Voltage Elimination with Reduced Common Mode Voltage Spikes in Multilevel Inverters with Extension to Over-Modulation Mode

Khoa-Dang Pham,Nho-Van Nguyen 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

This paper presents a pulse-width modulation strategy to eliminate the common mode voltage (CMV) with reduced CMV spikes in multilevel inverters since a high CMV magnitude and its fast variations dv/dt result in bearing failure of motors, overvoltage at motor terminals, and electromagnetic interference (EMI). The proposed method only utilizes the zero CMV states in a space vector diagram and it is implemented by a carrier-based pulse-width modulation (CBPWM) method. This method is generalized for odd number levels of inverters including neutral-point-clamped (NPC) and cascaded H-bridge inverters. Then it is extended to the over-modulation mode. The over-modulation mode is implemented by using the two-limit trajectory principle to maintain linear control and to avoid look-up tables. Even though the CMV is eliminated, CMV spikes that can cause EMI and bearing current problems still exist due to the deadtime effect. As a result, the deadtime effect is analyzed. By taking the deadtime effect into consideration, the proposed method is capable of reducing CMV spikes. Simulation and experimental results verify the effectiveness of the proposed strategy.

The complete chloroplast genome of purple longan (Dimocarpus longan Lour., Sapindaceae)

Pham Anh Thi Nguyen,Tan Khang Do,Thi Pha Nguyen,Van Be Nam Tran,Hoang Dang Khoa Do 국립중앙과학관 2024 Journal of Asia-Pacific Biodiversity Vol.17 No.1

Purple longan (Dimocarpus longan Lour.) is a new longan cultivar that arose in Soc Trang province,Vietnam. Although the economic value of purple longan has been revealed, genomic data have not beenexplored. In this study, the complete chloroplast genome of purple longan was sequenced and charac terized, which was 160,763 bp in length. The genome had a quadripartite structure, including a largesingle copy (85,628 bp), a small single copy (18,247 bp), and two inverted repeat (28,444 bp) regions. This genome contained 79 protein-coding genes, 30 transfer RNAs, and four ribosomal RNAs, of which, 16genes were duplicated in inverted repeat regions. Comparative genomic analysis revealed 11 highlyvariable regions (including matK-trnK_UUU, psbK-trnG_UCC, atpH-atpI, psbZ-rps14, pafI-trnL_UAA, psbJ petG, clpP, rpl36-rpl14, rpl32-ccsA, rps15-ycf1, and ycf1). Additionally, 100 insertion and deletion sites wereidentified in the purple longan chloroplast genome. This study provided the first report on the completechloroplast genome of purple longan, which is useful for further studies on cultivar identification,germplasm conservation, and plant breeding in the Dimocarpus genus and Sapindaceae family.

Pulse-Width Modulation Strategy for Common Mode Voltage Elimination with Reduced Common Mode Voltage Spikes in Multilevel Inverters with Extension to Over-Modulation Mode

Pham, Khoa-Dang,Nguyen, Nho-Van The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

This paper presents a pulse-width modulation strategy to eliminate the common mode voltage (CMV) with reduced CMV spikes in multilevel inverters since a high CMV magnitude and its fast variations dv/dt result in bearing failure of motors, overvoltage at motor terminals, and electromagnetic interference (EMI). The proposed method only utilizes the zero CMV states in a space vector diagram and it is implemented by a carrier-based pulse-width modulation (CBPWM) method. This method is generalized for odd number levels of inverters including neutral-point-clamped (NPC) and cascaded H-bridge inverters. Then it is extended to the over-modulation mode. The over-modulation mode is implemented by using the two-limit trajectory principle to maintain linear control and to avoid look-up tables. Even though the CMV is eliminated, CMV spikes that can cause EMI and bearing current problems still exist due to the deadtime effect. As a result, the deadtime effect is analyzed. By taking the deadtime effect into consideration, the proposed method is capable of reducing CMV spikes. Simulation and experimental results verify the effectiveness of the proposed strategy.

Neuromorphic Memristor Crossbars for Implementing Hierarchical Temporal Memory

Tien Van Nguyen,Khoa Van Pham,Kyeong-Sik Min 대한전자공학회 2019 대한전자공학회 학술대회 Vol.2019 No.6