• Title/Summary/Keyword: Sub System

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Novel Design of 8T Ternary SRAM for Low Power Sensor System

  • Jihyeong Yun;Sunmean Kim
    • Journal of Sensor Science and Technology
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    • v.33 no.3
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    • pp.152-157
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    • 2024

  • In this study, we propose a novel 8T ternary SRAM that can process three logic values (0, 1, and 2) with only two additional transistors, compared with the conventional 6T binary SRAM. The circuit structure consists of positive and negative ternary inverters (PTI and NTI, respectively) with carbon-nanotube field-effect transistors, replacing conventional cross-coupled inverters. In logic '0' or '2,' the proposed SRAM cell operates the same way as conventional binary SRAM. For logic '1,' it works differently as storage nodes on each side retain voltages of VDD/2 and VDD, respectively, using the subthreshold current of two additional transistors. By applying the ternary system, the data capacity increases exponentially as the number of cells increases compared with the 6T binary SRAM, and the proposed design has an 18.87% data density improvement. In addition, the Synopsys HSPICE simulation validates the reduction in static power consumption by 71.4% in the array system. In addition, the static noise margins are above 222 mV, ensuring the stability of the cell operation when VDD is set to 0.9 V.

  • https://doi.org/10.46670/JSST.2024.33.3.152 인용 PDF

Convolutionally-Coded and Spectrum-Overlapped Multicarrier DS-CDMA Systems in a Multipath Fading Channel

  • Oh, Jung-Hun;Kim, Ki-Doo;Milstein, Laurence B.
    • ETRI Journal
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    • v.23 no.4
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    • pp.177-189
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    • 2001

  • Multicarrier DS-CDMA is an effective approach to combat fading and various kinds of interference. In this paper, we present an overlapped multicarrier DS-CDMA system, wherein each of the rate 1/M convolutionally-encoded symbols is also repetition coded and transmitted using overlapped multicarriers. However, since the frequency spectrums of successive carriers are allowed to overlap, the transmission bandwidth is more efficiently utilized. The effect of the overlapping percentage between successive carriers of a multicarrier DS-CDMA system on the performance is investigated to determine the overlapping percentage showing the best performance. We suggest two methods for sub-band overlapping variation. One is to allow variation of sub-band overlapping percentage when the total number of subcarriers is fixed. The other is to increase the number of sub-bands (the number of repetitions R) with fixed sub-band bandwidth. Given a total number of subcarriers MR, we show that the BER variation is highly dependent on the roll-off factor ${\beta}$ of a raised-cosine chip wave-shaping filter irrespective of convolutional encoding rate 1/M and repetition coding rate 1/R. We also analyze the possibility of reduction in total multi-user interference by considering the variation of both the roll-off factor ($0<{\beta}{\leq}1$) and the sub-band overlapping factor ($0<{\lambda}{\leq}2$), and show that the proposed system may outperform the multicarrier DS-CDMA system in [3].

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The Design of Phase Angle Controller Reducing Sub-harmonic Current for Universal Motor in Vacuum Cleaner (진공청소기용 유니버셜모터의 고조파전류 저감 위상각제어기 설계)

  • 임홍우;장용해;백형래
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.3
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    • pp.237-243
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    • 2002

  • The single phase angle control system may become noisy when speed Is modulated with a conventional TRIAC AC controller. But this system is widely used despise of occurring sub-harmonic current because of its simply structure and low cost. Most of the vacuum cleaner drive control system regulates TRIAC's phase angle, so that it is controlled the speed. In the case of marketing product, it is not considered linearity of the speed to minimize occurring harmonic current. The sub-harmonic current reduces effectively in regulating specification TRIAC trigger phase angle. In this paper, we examined about characteristics of phase angle controller and parameter of parallel coil for eliminating sub-harmonic current.

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Joint Packet and Sub-carrier Allocation Scheme to Ensure Reliable Multimedia Service in OFDMA Multicast System (OFDMA 멀티캐스트 시스템에서 신뢰성 있는 멀티미디어 서비스를 보장하기 위한 패킷 및 서브 캐리어 할당 기법)

  • Gwak, Yong-Su;Kim, Yong-Young
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.4
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    • pp.8-12
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    • 2009

  • We propose BMPA(balanced multimedia packet allocation) scheme. This scheme considers the issue of optimal sub-carrier allocation in OFDMA multicast system. When RT(real time) packets and NRT(non-real time) packets arrive at the same time, BMPA scheme gives higher weight to RT packets than NRT packets and then, it allocates sub-carriers according to the total weight sum of packets in each user. This process acts as both packet scheduler and sub-carrier allocation. Therefore, each user receives multimedia packets with reliability. With simulation results, it shows that BMPA scheme ensures long-term system throughput and, in average RT packet delay, BMPA scheme greatly outperforms multi-user water-filling algorithm.

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