• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.333-336
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• 2000

Modem standard CMOS process technology suffer from so large amount of PVT i.e process, voltage and temperature variation over 30% of its desired value that accurate resistor value is hard to be achieved. A filter using switched-capacitor(SC) circuit has a time constant proportional to relative capacitor area ratio rather than its absolute value. If the PLL's loop filter were made out of SC circuit, there could be much less PVT variation problem. Furthermore, programmability on the loop filter can be achieved In this paper, we present the PLL with SC loop filter. The accuracy provided by SC filter would be helpful to enhance PLL's locking behaviour.

• 전기학회논문지
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• 제64권8호
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• pp.1180-1185
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• 2015

This paper describes the accurate inductance measurement of a switched reluctance motor (SRM). Conventionally, the inductance of the SRM is measured using the equivalent circuit of a stator phase or time constant of exponential current transient. This paper presents an effective method to measure the SRM inductance accurately and rapidly using automated voltage integration. The proposed method is validated experimentally by comparison with the existing equivalent circuit method (ECM) and the FEA(finite element analysis) simulation.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권3호
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• pp.417-422
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• 2015

A 6.5 - 8.5 GHz CMOS UWB transmitter is implemented using $0.18{\mu}m$ CMOS technology. The transmitter is mainly composed of switched LC VCO and digital pulse generator (DPG). Using RF switch and DPG, the uniform power and sidelobe rejection are achieved irrespective of the carrier frequency. The measured UWB carrier frequency range is 7 ~ 8 GHz and the pulse width is tunable from 1 to 2 ns. The measured energy efficiency per pulse is 2.1 % and the power consumption is 0.6 mW at 10 Mbps without the buffer amplifier. The chip core size is $0.72mm^2$.

• Journal of Power Electronics
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• 제19권1호
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• pp.1-10
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• 2019

Current imbalance is the main factor affecting the lifespan of light-emitting diode (LED) lighting systems and is generally solved by active or passive approaches. Given many new lighting applications, independent control is particularly important in achieving different levels of luminance. Existing passive and active approaches have their own limitations in current sharing and independent control, which bring new challenges to the design of LED drivers. In this work, a multichannel resonant converter based on switched-capacitor control (SCC) is proposed for solving this challenge. In the resonant network of the upper and lower half-bridges, SCC is used instead of fixed capacitance. Then, the individual current of the LED array is obtained through regulation of the effective capacitance of the SCC under a fixed switching frequency. In this manner, the complexity of the control unit of the circuit and the precision of the multichannel outputs are further improved. Finally, the superior performance of the proposed LED driver is verified by simulations and a 4-channel experimental prototype with a rated output power of 20 W.

• 센서학회지
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• 제25권5호
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• pp.326-332
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• 2016

A novel CMOS temperature sensor with binary output is implemented by using fully differential switched-capacitor circuits for resistorless implementation of the temperature sensor core. Temperature sensing is based on the temperature characteristics of the pn diodes implemented by substrate pnp transistors fabricated using standard CMOS processes. The binary outputs are generated by using the charge-balance principle that eliminates the division operation of the PTAT voltage by the bandgap reference voltage. The chip was designed in a MagnaChip $0.35-{\mu}m$ CMOS process, and the designed circuit was verified using Spectre circuit simulations. The verified circuit was laid out in an area of $950{\mu}m{\times}557 {\mu}m$ and is currently under fabrication.

• 전력전자학회논문지
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• 제10권4호
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• pp.388-396
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• 2005

SRM은 각종 산업분야에서 토크 리플과 소음 진동, 낮은 역률로 인하여 실제 적용에는 어려움이 있고 구동을 하기 위해서는 회전자위치 정보를 위한 센서가 필요하다. 따라서 본 논문에서는 전압펄스 주입방식을 이용한 센서리스 방식을 제안하였다. 기존 전압펄스 주입방식의 문제점인 위상지연 문제와 기존 센서리스 방식의 어려움이라 할 수 있는 초기구동 문제를 제안하였다. 또한 고성능 마이크로프로세서를 사용한 복잡한 연산과정 없이 단순한 범용 아날로그 소자만으로도 간단히 센서리스 방식을 구현하였다.

• Journal of Communications and Networks
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• 제4권3호
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• pp.230-245
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• 2002

Usually the network-throughput maximization problem for constant-bit-rate (CBR) circuit-switched traffic is posed for a fixed offered load profile. Then choices of routes and of admission control policies are sought to achieve maximum throughput (usually under QoS constraints). However, similarly to the notion of channel “capacity,” it is also of interest to determine the “network capacity;” i.e., for a given network we would like to know the maximum throughput it can deliver (again subject to specified QoS constraints) if the appropriate traffic load is supplied. Thus, in addition to determining routes and admission controls, we would like to specify the vector of offered loads between each source/destination pair that “achieves capacity.” Since the combined problem of choosing all three parameters (i.e., offered load, admission control, and routing) is too complex to address, we consider here only the optimal determination of offered load for given routing and admission control policies. We provide an off-line algorithm, which is based on Lagrangian techniques that perform robustly in this rigorously formulated nonlinear optimization problem with nonlinear constraints. We demonstrate that significant improvement is obtained, as compared with simple uniform loading schemes, and that fairness mechanisms can be incorporated with little loss in overall throughput.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.631-634
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• 1999

A new multiple-output dc-to-dc converter based on a switched capacitor circuit is proposed. The proposed converter offers multiple outputs that can be individually regulated by a direct output voltage feedback or indirect cross regulations. The performance of the new converter is demonstrated using a 10W experimental converter that delivers 5V/1A output and 3.3V/1A output from a 10∼15V input source.

• 대한전자공학회논문지
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• 제26권11호
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• pp.1666-1671
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• 1989

A novel switched-capacitor circuit for interfacing capacitive microtransducers with a digital system is developed based on the dual-slope integration. It consists of a differential integrator and a comparator. Driven by the teo phase clock, the circuit first senses the capacitance difference between the transducer and the reference capacitor in the form of charge, and accumulates it into the feedback capabitor of the integrator for a fixed period of time. The resulant accumulated charge is next extracted by the known reference charge until the integrator output voltage refurns to zero. The length of time required for the integrator output to return to zero, as measured by the number of clock cycle gated into a counter is proportional to the capacitance difference, averaged over the integration period. The whole operation is insensitive to the reference voltage and the capacitor values involved in the circuit, Thus the proposed circuit permits an accurate differental capacitance measurement. An error analysis has showh that the resolution as high as 8 bits can be expected by realizing the circuit in a monolithic MOS IC form. Besides the accuracy, it features the small device count integrable onto a small chip area. The circuit is thus particularly suitadble for the on-chip interface.

• 센서학회지
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• 제31권2호
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• pp.115-119
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• 2022

A readout circuit for a mercury-cadmium-telluride (MCT)-amplified mid-wave infrared (IR) photodetector was realized and applied to noncontact chemical agent detectors based on a quantum cascade laser (QCL). The QCL emitted 250 times for each wavelength in 0.2-㎛ steps from 8 to 12 ㎛ with a frequency of 100 kHz and duty ratio of 10%. Because of the nonconstant QCL emission power during on-duty, averaging the photodetector signals is essential. Averaging can be performed in digital back-end processing through a high-speed analog-to-digital converter (ADC) or in analog front-end processing through an integrator circuit. In addition, it should be considered that the 250 IR data points should be completely transferred to a PC during each wavelength tuning period of the QCL. To average and minimize the IR data, we designed a readout circuit using the analog front-end processing method. The proposed readout circuit consisted of a switched-capacitor integrator, voltage level shifter, relatively low-speed analog-to-digital converter, and micro-control unit. We confirmed that the MCT photodetector signal according to the QCL source can be accurately read and transferred to the PC without omissions.