• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.6
• /
• pp.287-290
• /
• 2006

A class-E CMOS RF(Radio frequency) power amplifier with a 1.8 Volt power supply is designed using $0.25{\mu}m$ standard CMOS technology. To drive the class-E power amplifier, a Class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. After one year of operating the power amplifier with an RF choke, the PAE(Power Added Efficiency) decreases from 60% to 47% and the output power decreases 29%. However, when a finite DC-feed inductor is used with the load, the PAE decreases from 60% to 53% and the output power decreases only 19%. The simulated results demonstrate that the class-E power amplifier with a finite DC-feed inductor exhibits superior reliability characteristics.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.3
• /
• pp.133-139
• /
• 2003

In this paper, a new control scheme of Class-E inverter for Induction Heating (IH) Jar applications with clamped voltage characteristics using Pulse-Frequency-Modulation (PFM) is introduced. To reduce the voltage stress of switch, the proposed PFM control scheme doesn't need any auxiliary circuit in comparison to a family of Active Clamped Class-E (ACCE) inverter. It can decrease voltage stress of switch through modulation of switching frequency. The Class-E inverter using the proposed control scheme has the advantage of not only the same output power when it is compared with a Hybrid-Active Clamped Class-E (Hybrid-ACCE) inverter but also Zero-Voltage-Switching (ZVS), which are characteristics of conventional Class-E and ACCE inverter. The control principles and analysis of proposed method are explained in detail and its validity is verified through simulation and experimental results.

• Journal of Information Technology Applications and Management
• /
• v.15 no.2
• /
• pp.33-49
• /
• 2008

The purpose of this study is to find student factors associated with the students' evaluation of university teaching, and to provide a meaningful reference to policy-making of teaching evaluation. Based on the surveyed questionnaires from 232 students who participated in e-learning course. in combination with applying descriptive statistics, this study analyzes (1) the influences of students' pre-motivation level of student based-on ARCS theory on class satisfaction, (2) the influences of students' grade, attendance, and class involvement on class satisfaction, and (3) the influences of e-learning experience on students' pre-motivation level and class satisfaction. Result of this study shows that: (1) students' pre-motivation level including Attention(A), Relevance(R), Confidence(C), and Satisfaction(S) is positively correlated to students' evaluation for teaching, (2) students' grade, attendance. and class involvement are positively correlated to students' evaluation for teaching, and (3) students' e-learning experience is not related with students' pre-motivation level, whereas it is related with class satisfaction.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.11
• /
• pp.98-102
• /
• 2011

This paper describes inverse E class frequency multiplier which is lower inductance and peak switching voltage than E class frequency multiplier. The frequency multiplier is designed to generate 5.8[GHz] frequency by doubling the input frequency 2.9[GHz]. The peak switching voltage of designed inverse E class frequency multiplier with 11[V] is lower 4[V] than that of E class frequency multiplier with 15[V]. The inverse E class frequency multiplier has a conversion gain 6[dB] at output power 21[dBm] and maximum 35[%] power efficiency.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.681-682
• /
• 2013

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.12
• /
• pp.1-6
• /
• 2008

In this paper, bias control circuit structure have been employed to improve the power added efficiency of the CMOS class-E power amplifier on low input power level. The gate and drain bias voltage has been controlled with the envelope of the input RF signal. The proposed CMOS class-E power amplifier using bias controlled circuit has been improved the PAE on low output power level. The operating frequency is 2.14GHz and the output power is 22dBm to 25dBm. In addition to, it has been evident that the designed the structure has showed more than a 80% increase in PAE for flatness over all input power level, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.8
• /
• pp.805-808
• /
• 2011

This paper presents a design of high-efficiency and high-power class E power transmitter. The transmitter is composed of 300 Watt class E power amplifier and AC-DC converter. The AC-DC converter converts 220 V and 60 Hz AC to a 290 V DC. The generated DC voltage is directly applied to a bias of the class E power amplifier. Because the converter does not have DC-DC converter unit, it has very high conversion efficiency of about 98.03 %. To minimize the loss at the output of the power amplifier, high-Q inductor was implemented and deployed to the output resonant circuit. As a result, the 13.56 MHz class E power amplifier has a high power-added efficiency of 84.2 % at the peak output power of 323.6 W. The overall efficiency of class E power transmitter, including the AC-DC converter, is as high as 82.87 %.

• Journal of information and communication convergence engineering
• /
• v.6 no.2
• /
• pp.154-157
• /
• 2008

A class-E RF(Radio Frequency) power amplifier for wireless application is designed using standard CMOS technology. To drive the class-E power amplifier, a class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. The reliability characteristic is improved when a finite-DC feed inductor is used instead of an RF choke with the load. After one year of operating, when the load is an RF choke the output current and voltage of the power amplifier decrease about 17% compared to initial values. But when the load is a finite DC-feed inductor the output current and voltage decrease 9.7%. The S-parameter such as input reflection coefficient(S11) and the forward transmission scattering parameter(S21) is simulated with the stress time. In a finite DC-feed inductor the characteristics of S-parameter are changed slightly compared to an RF-choke inductor. From the simulation results, the class-E power amplifier with a finite DC-feed inductor shows superior reliability characteristics compared to power amplifier using an RF choke.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.220-225
• /
• 2018

A class E power oscillator is demonstrated for 6.78-MHz wireless power transfer system. The oscillator is designed with a class E power amplifier to use an LC feedback network with a high-Q inductor between the input and the output. Multiple capacitors are used to minimize the variation of the oscillation frequency by capacitance tolerance. The gate and drain bias voltages with opposite characteristics to make the frequency shift of the oscillator are connected in a resistance distribution circuit located at the output of the low drop-out regulator and supplied bias voltages for class E operation. The measured output of the class E power oscillator, realized using the co-simulation, shows 9.2 W transmitted power, 6.98 MHz frequency and 86.5% transmission efficiency at the condition with 20 V $V_{DS}$ and 2.4 V $V_{GS}$.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.1
• /
• pp.83-88
• /
• 2007

The reliability characteristics of class-E RF power amplifier are studied, based on the degradation of MOSFET electrical characteristics. The class-E power amplifier operates as a switch mode operation to achieve high efficiency. This operation leads to high voltage stress when MOSFET switch is turned-off. The increase in threshold voltage and decrease in nobility caused by high voltage stress leads to a drop in the drain current. In the class-E power amplifier the effects caused by the degradation of MOSFET drain current is a drop of the power efficiency and output power. But the small inductor in the class-E load network allows the reliability to be improved. After $10^{7}\;sec$. the drain current decreases 46.3% and the PAE(Power Added Efficiency) decreases from 58% to 36% when the load inductor is 1mH. But when the load inductor is 1nH the drain current decreases 8.89% and the PAE decreases from 59% to 55%.