• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.4
• /
• pp.63-72
• /
• 2007

In this paper, we propose a novel reconfigurable coprocessor for multimedia mobile terminals. Because most of multimedia operations require fast operations of large amount of data in the limited clock frequency, it is necessary to enhance the performance of the embedded processor that is widely used in current multimedia mobile terminals. Therefore, we proposed and have designed the coprocessor which had the ability of fast operations of multimedia data. The proposed coprocessor was not only reconfigurable, but also flexible and expandable. The proposed coprocessor has been designed by using VHDL and compared with previous reconfigurable coprocessors and a commercial embedded processor in architecture and speed. As a result of the architectural comparison, the proposed coprocessor had better structure in terms of hardware size and flexibility. Also, the simulation results of DCT application showed that the proposed coprocessor was 26 times faster than a commercial ARM processor and 11 times faster than the ARM processor with fast DCT core.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.12
• /
• pp.7287-7291
• /
• 2014

A CDTA (current differencing transconductance amplifier) is an active building block for current mode analog signal processing with the advantages of high linearity and a wide frequency bandwidth. In addition, it can generate a stable voltage because all the differencing input current flows to the grounded devices. In this paper, a new small signal equivalent circuit is proposed to analyze a CDTA. The proposed small signal equivalent circuit provides greater precision in analyzing the magnitude and frequency response than its previous counterparts because it considers the parasitic components of the input, internal and output terminal. In addition, observations of the changes made in various devices, such as the resistor (Rz) confirmed that those devices heavily influence the characteristics of CDTA. The designed parameters of the proposed small signal equivalent circuit of the CDTA provides convenience and accuracy in the further design of analog integrated circuits. For verification purposes, a 2.5 MHz low pass filter was designed on the HSPICE simulation program using the proposed small signal equivalent circuit of CDTA.

• Smart Media Journal
• /
• v.4 no.2
• /
• pp.55-61
• /
• 2015

A bandwidth-enhanced ultra-wide band (UWB) CMOS balun-LNA is implemented as a part of a software defined radio (SDR) receiver which supports multi-band and multi-standard. The proposed balun-LNA is composed of a single-to-differential converter, a differential-to-single voltage summer with inductive shunt peaking, a negative feedback network, and a differential output buffer with composite common-drain (CD) and common-source (CS) amplifiers. By feeding the single-ended output of the voltage summer to the input of the LNA through a feedback network, a wideband balun-LNA exploiting negative feedback is implemented. By adopting a source follower-based inductive shunt peaking, the proposed balun-LNA achieves a wider gain bandwidth. Two LNA design examples are presented to demonstrate the usefulness of the proposed approach. The LNA I adopts the CS amplifier with a common gate common source (CGCS) balun load as the S-to-D converter for high gain and low noise figure (NF) and the LNA II uses the differential amplifier with the ac-grounded second input terminal as the S-to-D converter for high second-order input-referred intercept point (IIP2). The 3 dB gain bandwidth of the proposed balun-LNA (LNA I) is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average power gain of 18 dB and an IIP3 of -8 ~ -2 dBm are obtained. In simulation, IIP2 of the LNA II is at least 5 dB higher than that of the LNA I with same power consumption.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.10
• /
• pp.77-82
• /
• 2004

This paper presents polar converting logic(PCL) of BTT missiles against slowly moving or stationary targets. A guidance commands expressed in rectangular coordinates must be converted in the form of polar coordinates for BTT control. Since conventional PCL has nonlinear and discontinuous function, the missiles may lose controllability when pitch acceleration command equals to zero. Further, roll coupling may have a serious unstabilizing influence on homing guidance with two gimbals seeker. In this paper, a linear homotopy equation is introduced to improve the controllability and a command following performance at midcourse phase. We also design a PCL which is less sensitive to pitch acceleration command so that it may improve the stability of the homing loop. To substantiate our conclusion, results of the computer simulation have been illustrated.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.11
• /
• pp.828-835
• /
• 2001

Novel bipolar transresistance amplifier(TRA) and its offset-compensated TRA for high-performance current-mode signal processing are described. The TRA consist of two current follower for a current inputs, a current summer for the current-difference, a resistor for the current to voltage converter, and a voltage follower for the voltage output. The offset-compensated TRA adopts diode-connected npn and pnp transistor to reduce offset voltage in the TRA. The simulation results show that the TRA has impedance of 0.5 Ω at the input and the output terminal. The offset voltages at these terminals is 40 mV The offset-compensated TRA has the offset voltage of 1.1 mV and the impedance of 0.25 Ω. The 3-dB cutoff frequency is 40 MHz for the two TRA＇s when used as a current to voltage converter with unit-gain transresistance. The power dissipation is 11.25 mW.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.11B
• /
• pp.1373-1382
• /
• 2011

Zigbee is communication technology most ideal because Zigbee support low power communication and wide expansion in wireless home network. However, Zigbee is not popular, because of Zigbee always has Hidden Node Problem and Transit Delay Problem. We propose new Beacon Frame structure to solve the two problem in Zigbee. New Beacon Frame structure reduces a Super Frame Duration and add a same space of a Control Frame Duration. We expect to solved method of Hidden Node Problem that exchange terminal information to using RTS/CTS. Also, We expect to solved method of Transit Delay Problem that put Beacon between Control Frame Duration and Super Frame Duration for synchronization. We confirm new Beacon Frame to solved two problem in OPNET simulation at Zigbee QoS Parameters. We measure Delay(sec) for solution degree of Transit Delay Problem, and measure Throughput(bits/sec) and Load (bits/sec) for solution degree of Hidden Node Problem.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.6
• /
• pp.665-670
• /
• 2015

In this paper, We proposed a broadband RF amplifier for Microwave band receiver. We also proposed a broadband RF amplifier, designed by using EM simulation for reliable amplification of the received signal. Connected to a source terminal to via, it minimizes those which are the active elements of source-side oscillation as the operating element in an ideal GND, and a constant gain characteristic in a broadband. The goal of this was to obtain stable amplification characteristics. For implementing this architecture, we designed the broadband(500 MHz ~ 7 GHz) RF amplifier by using commercial GaAs FET, which operate on 720 MHz, 4,595 MHz, and 6,035 MHz by impedance matching. The voltage gain is 10.635 dB ~ 14.407 dB(737.5 MHz ~ 6.0575 GHz), P1dB is 20 dBc of band(1st harmonic/2nd harmonic).

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.6
• /
• pp.1416-1422
• /
• 2010

Various other platforms have appeared due to the abolishment of WIPI requirement and increased problems related with hacking and security. Since levels consisting of these platforms are composed of various APIs (Application Programming Interfaces) which are not standardized, other ways must be considered to protect data which are transferred using XML formats. Therefore, XML encryption API and XML digital signature API for data protection and certification, which are both responsible to define mark-up languages for XML encryption and digital signature respectively, were designed in this paper. The simulation system which played the role of the server and client between two terminal units was realized to validate the APIs.

• Journal of IKEEE
• /
• v.2 no.1 s.2
• /
• pp.15-23
• /
• 1998

In this paper, distributed mixer is studied at microwave frequency. The circuit of distributed mixer composed of gate 1,2, drain transmission lines, matching circuits in input and output terminal, DGFET's. For impedance matching of input and output port at higher frequency, image impedance concept is introduced. In distributed mixer, a DGFET's impedances are absorbed by artificial transmission line, this type of mixer can get a very broadband characteristics compared to that of current systems. A RF/LO signal is applied to each gate input port, and are excited the drain transmission line through transcondutance of the DGFET's. The output signals from each drain port of DGFET's added in same phases. We designed and frabricated the distributed mixer, and a conversion gain, noise figure, bandwidth, LO/RF isolation of the mixer are shown through computer simulation and experimentation.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.12
• /
• pp.117-128
• /
• 2013

u-safety service system inter-works with the diverse operation agencies, through CCTV network, such as the emergency call terminal with built-in GPS, the mobile communication network, u-safety service provider, relay system and CCTV control center. In the case of the emergency call, this service searches the location of caller in real time, and then continues to search the location of caller through the control of CCTV in the searched place, and can provide the several agencies like guardian, police office, fire station, hospitals, relief organizations and municipalities, with the diverse information necessary for the secure rescue through SMS and wired network. In this paper, a new protocol and specification for u-safety service relay system is designed and implemented. The effectiveness of presented protocol is verified by computer simulation. The designed protocol of u-safety service is applied to real 3GPP and 3GPP2 mobile communication networks to verify its performance.