• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.60-68
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• 2016

This paper presents a 6~18 GHz 7-bit digital-controlled attenuator. The proposed attenuator is based on switched-T architecture, but no inductor is used for minimum chip size. The designed attenuator was fabricated using $0.18{\mu}m$ CMOS process, and characterized using on-wafer testing setup. The resolution(minimum attenuation step) and the maximum attenuation range of the attenuator were measured to be 0.22 dB and 28 dB, respectively. The measured RMS attenuation error and the RMS phase error for 6~18 GHz were less than 0.26 dB and $3.2^{\circ}$, respectively. The reference state insertion loss was less than 12.4 dB at 6~18 GHz. The measured input and output return losses were better than 9.4 dB over all frequencies and attenuation states. The chip size is $0.11mm^2$ excluding pads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4984-4990
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• 2010

In this paper, a Step-down CMOS DC-DC Converter using low power switched capacitor method is designed in a 0.5 ${\mu}m$ technology for the integration of devices. Conventional DC-DC converter is used inductor that can store energy in a magnetic field but have low efficiency because power consumption is caused by magnetic flux. And there were problems with size, weight and price to integrate chip. In this paper, a proposed Inductorless step-down CMOS DC-DC converter of low power using SC method is designed in a 0.5um technology to solve these problems. Designed DC-DC converter have 96% power efficiency with 200kHz frequency by using cadence simulation.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.627-633
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• 2011

DC/DC switching power converters are commonly used to generate a regulated DC output voltages with high efficiencies from different DC input sources. The voltage mode DC/DC converter utilizes MOSFET, inductor, and a PWM (pulse-width modulation) controller with oscillator, amplifier, and comparator, etc. to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter and a buck converter containing a switched-mode power supply are studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by program of SPICE. In addition, power efficiency is analyzed based on the specification of each component.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.261-263
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• 2006

A new soft switched active snubber circuit is proposed to achieve zero voltage and zero current switching for all the switching devices in PWM DC-DC converters. The unique location of the snubber and inductor ensures low current/voltage stresses and commutation losses. With a saturable reactor, the conduction loss of auxiliary switch could be further minimized. A boost converter adopting this technique is presented as an example, to illuminate its operation principles and derive the design procedures. Simulation and hardware implementation have been made to validate its performance. Some other basic PWM DC-DC topologies using the proposed snubber have also been given.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.3
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• pp.201-205
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• 2010

DC/DC Switching power converters are commonly used to generate regulated DC output voltages with high-power efficiencies from different DC input sources. A switching converter utilizes one or more energy storage elements such as capacitors, or transformers to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter studied here consists of a power metal-oxide semiconductor field effect transistor switch, an inductor, a capacitor, a diode, and a pulse-width modulation circuit with oscillator, amplifier, and comparator. A buck converter containing a switched-mode power supply is also studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by simulation program with integrated circuit emphasis (SPICE). Furthermore, power efficiency was analyzed based on the specifications of each component.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.438-439
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• 2011

In this paper, soft switching bidirectional DC-DC converter is proposed. The proposed topology is added two auxiliary switches, two resonant capacitors and one resonant inductor to convectional bidirectional DC-DC converter. Therefore, this proposed topology can reduce switching loss of each power switch by ZVS (Zero Voltage Switching) and ZCS (Zero Current Switching). We have performed mode analysis, simulation and experiment for the proposed topology.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.60-63
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• 1998

The widely used power supply (Switched Mode Power Supply : SMPS) as a source in order to stabilize direct current for electronics or communication systems has merits, when it is compared to the existing source for stability, such as high efficiency, small size, light weight by means of switching process of the semiconductor device which controls the flow of power. However, due to existence of inductors and capacitors used for charging energy, the source part in electronic or communication systems hasn't reached the speed, that is supposed to get, for achieving smaller size and lighter weight. In order to get smallness in size, it is necessary to increase switching frequency. And that makes devices for measuring energy smaller. Nevertheless, the rise switching frequency brings increases in switching loss, inductor loss, and power loss. Also, the occurrence of surge and noise caused by high frequency switching is getting higher. The resonant converter has been considered as one of methods that give solutions for the problems of SMPS and that method have been paid attention as a source technology in electronics and communication.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.77-85
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• 2009

With the advent of power semiconductor switching devices, power electronics relating to high frequency electromagnetic eddy current based induction heating technology have become more suitable and acceptable. This paper presents high-frequency induction heating cooking appliance circuit based on the zero current switching-PWM single ended push-pull(ZCS-PWM SEPP) resonant inverter added AC-DC converter. This inverter uses pulse-width-modulation(PWM) control method with active auxiliary quasi-resonant lossless inductor snubbers and a switched capacitor. To improved the transient performance, the PI controller is applied for this system. For the systematic parameter optimization of the PI controller, the gradient-based optimization algorithm is applied. The performance of optimized parameters is evaluated using simulation and experimental test. These results show that the proposed systematic optimal tuning method improve the transient performances of this system.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1010-1011
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• 2006

A new soft switched active snubber circuit is proposed to achieve zero voltage and zero current switching for all the switching devices in PWM DC-DC converters. The unique location of the snubber capacitor and inductor ensures low current/voltage stresses and commutation losses. With a saturable reactor, the conduction loss of the auxiliary switch could be further minimized. A boost converter adopting this technique is presented as an example, to illuminate its operation principles and derive the design procedures. Simulation and hardware implementation have been made to validate its performance. Some other basic PWM DC-DC topologies using the proposed snubber have also been given.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.1
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• pp.10-17
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• 2002

Due to the development of information communication field, the interest of the SMPS(Switched Mode Power Supply) is increased. The size and weight of SMPS are decided by inductor, capacitor and transformer. Thus, the low loss converter which is operated in high speed switching is required. The resonant FB DC-DC converter is able to operate in high speed switching and apply to high power field because the switching loss is low. In this thesis, it is proposed to control strategy for constant output power of resonant FB DC-DC converter in variable input voltage. The proposed control system is a digital I-PD type control and apply to phase-shift resonant type controller. The output voltage tracks reference without steady state error in variable input voltage. The validity of proposed control strategy is verified from results of simulation and experiment.