• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.1
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• pp.28-36
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• 2008

This paper discusses theimplementation of the low-voltage, low-power, third-order, 1-bit switched capacitor delta-sigma modulator of the implantable cardiac pacemaker. The distributed, feed-forward structure and bulk-driven OTA were used in order to achieve an efficient operation under a supply voltage of 1V or lower. The designed modulator has a dynamic range of 49dB at 0.9V supply voltage and consumes 816nW of power. Such a significant reduction in power consumption allows diverse applications, not only in pacemakers, but also in implantable biomedical devices that operate with limited battery power. The core chip size of the modulator is $1000{\mu}m*500{\mu}m$ manufactured, with the $0.18{\mu}m$ CMOS standard process.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.9
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• pp.6-12
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• 1999

It is difficult to realize adaptive main carrier rejection circuit in feedforward-type LPA(Linear Power Amplifier) because the gain and nonlinear characteristics of power amplifier are changed according to operating frequency, voltage, temperature. Usually, pilot tones are used for adaptive LPA operation. but in this paper, the relative phase, which in obtained through I&Q demodulator using input signals as LO signals and main-path & sub-path signals as RF signals, and the magnitude of main-path & sub-path signals are compared, so main carrier rejection is obtained. The proposed method rejects main carriers by 28.34 ~ 34.66dB (@Po=36.2 ~ 28.2 dBm/tone) with two tones at 877MHz, 882MHz and also rejects main carriers by 31.3dB despite changing condition of operating voltage.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.231-239
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• 1998

This paper presents the dynamic analysis and control loop design of a zero voltage switching full bridge (ZVS-FB) PWM DC/DC converter. The small-signal model is derived incorporating the effects of phase shift control and the utilization of transformer leakage inductance and power FET junction capacitance to achieve zero voltage resonant switching. These effects are modeled by introducing additional feedforward and feedback terms for duty cycle modulation. Based on the results of the small-signal analysis, the control loop is designed using a simple two-pole one-zero compensation circuit. To show the validity of the design procedures, the small signal analysis of the closed loop system is carried out and the potential of the zero voltage switching and the superiority of the dynamic characteristics are verified through the experiment with a 2 kW prototype converter.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.51-59
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• 2009

This paper presents the design of continuous-time sigma-delta modulator for acoustic sensor. The feedforward structure without summing block is used to reduce power consumption of sigma-delta modulator. A high-linearity active-RC filter is used to improve resolution of sigma-delta modulator. Excess loop delay problem in conventional continuous-time sigma-delta modulators is solved by our proposed architecture. A low power, high resolution fourth-order continuous-time sigma-delta modulator with 1-bit quantization was realized in a 0.13-${\mu}m$ 1-Poly 8-metal CMOS technology, with a core area of $0.58\;mm^2$. Simulation results show that the modulator achieves 91.3-dB SNR over a 25-kHz signal bandwidth with an oversampling ratio of 64, while dissipating $290{\mu}W$ from a 3.3-V supply.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.983-985
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• 2002

This paper is the machine that is able to estimate a new built power convertor in a production line. Generally, this machine test can be achieved by connecting it to a dynamometer consisting of a three-phase machine joined by a rigid shaft to a DC load machine. But the proposal system is controlled to create some specific load characteristic needed for the test without any mechanical equipment. The suggested test stand consists only of a converter to be test and a simulator converter. Both devices are connected back-to-back on the AC-side via smoothing reactors. The simulator operates in real-time as an equivalent load circuit, so that the device under test will only notice the behaviour of a three-phase machine under consideration of the load. And then, to obtain a superior characteristic for dynamic reference used the feedforward control.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1480-1491
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• 2015

In new deregulated electricity market, short-term price forecasting is key information for all market players. A better forecast of market-clearing price (MCP) helps market participants to strategically set up their bidding strategies for energy markets in the short-term. This paper presents a new prediction strategy to improve the need for more accurate short-term price forecasting tool at spot market using an artificial neural networks (ANNs). To build the forecasting ANN model, a three-layered feedforward neural network trained by the improved Levenberg-marquardt (LM) algorithm is used to forecast the locational marginal prices (LMPs). To accurately predict LMPs, actual power generation and load are considered as the input sets, and then the difference is used to predict price differences in the spot market. The proposed ANN model generalizes the relationship between the LMP in each area and the unconstrained MCP during the same period of time. The LMP calculation is iterated so that the capacity between the areas is maximized and the mechanism itself helps to relieve grid congestion. The addition of flow between the areas gives the LMPs a new equilibrium point, which is balanced when taking the transfer capacity into account, LMP forecasting is then possible. The proposed forecasting strategy is tested on the spot market of the Nord Pool. The validity, the efficiency, and effectiveness of the proposed approach are shown by comparing with time-series models

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2876-2878
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• 2005

In this paper, we propose Genetic Algorithms(GAs)-based Optimal Polynomial Neural Networks(PNN). The proposed algorithm is based on Group Method of Data Handling(GMDH) method and its structure is similar to feedforward Neural Networks. But the structure of PNN is not fixed like in conventional Neural Networks and can be generated. The each node of PNN structure uses several types of high-order polynomial such as linear, quadratic and modified quadratic, and is connected as various kinds of multi-variable inputs. The conventional PNN depends on experience of a designer that select No. of input variable, input variable and polynomial type. Therefore it is very difficult a organizing of optimized network. The proposed algorithm identified and selected No. of input variable, input variable and polynomial type by using Genetic Algorithms(GAs). In the sequel the proposed model shows not only superior results to the existing models, but also pliability in organizing of optimal network. The study is illustrated with the ACI Distance Relay Data for application to power systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.831-835
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• 2016

In this paper, a dual-channel feed-forward transimpedance(TIA) array is realized in a standard $0.18-{\mu}m$ CMOS technology which exploits automatic gain control function to provide 40-dB input dynamic range for either detecting targets nearby or sensing imminent danger situations. Compared to the previously reported conventional feed-forward TIA, the proposed automatic-gain-control feed-forward TIA(AFF-TIA) extends the input dynamic range 25 dB wider by employing a 4-level automatic gain control circuit. Measured results demonstrate the linearly varying transimpedance gain of 47 to $72dB{\Omega}$, input dynamic range of 1:100, the bandwidth of $${\geq_-}670MHz$$, the equivalent input referred noise current spectral density of 6.9 pA/${\surd}$HZ, the maximum sensitivity of -26.8 dBm for $10^{-12}BER$, and the power consumption of 27.6 mW from a single 1.8-V supply. The dual-channel chip occupies the area of $1.0{\times}0.73mm^2$ including I/O pads.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1376-1385
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• 2000

The phase characteristic of delay line in feedfarward linearizer has been changed due to variation of operating temperature. In this paper, design method of fixed phase control circuit of group delay line using adaptive vector control is derived. To maintain transfer characteristics of nominal operating temperature, the error correlated signals, which are changed adaptively due to changing of temperature, are added to main signals. The proposed method maintains transfer characteristics under 0.06dB of insertion loss and 0.36$^{\circ}$ of phase variation in case of 1-tone(880 MHz) and under 0.07 dB of insertion loss and 0.35$^{\circ}$ of phase variation in case of 2-tones(877 MHz, 882 MHz) for 10dB input power dynamic range and +/-10$^{\circ}$ phase variation respectively.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.359-360
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• 2012

This paper proposes a scheme of auto-tuning fuzzy PI controller and input voltage feed forward to control the output voltage of a three-phase Z-source inverter (ZSI). The proposed scheme adjusts the ts (Kp and Ki) in real time in order to find the most suitable Kp and Ki for PI controller and to simplify the controller design. The proposed scheme is verified the validity by experiment and co-simulation in PSIM and MATLAB/SIMULINK both load step change and input DC voltage variation in Z-source inverter, and has compared with the conventional PID control scheme. The experiment results involve of three-phase output voltage, Z-network capacitor voltage and dc-link peak voltage value. By those analysis and comparison, the availability of the proposed method in output voltage transient response quality improving has been verified. Compared with conventional PID method, the proposed method showed a more effective and robust control performance for coping with the severe disturbance conditions.