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Performance Comparison between Inverse Class-F and Class-F Amplifiers Based on the Waveform Analysis
Youngoo Yang,Young Yun Woo,Bumman Kim 한국전자파학회JEES 2002 Journal of Electromagnetic Engineering and Science Vol.2 No.1
We have analyzed the inverse class-F and class-F amplifiers using their waveforms. From the analytic equations derived from the analysis, we gave calculated the efficiencies, output powers, DC power dissipations, and optimum fundamental load impedances of the inverse class-F and class-F amplifiers. We also have compared them for various operation conditions, which include the same peak current, same DC power dissipation, same fundamental RF output power, and same fundamental load impedance with different Ron(on-resistance). These analyses have clearly shown the performance limitations, advantages, and guide to the optimized design of the inverse class-F amplifiers.
Lee, DongSoo,Cho, SungHun,Ryu, Hocheol,Pu, YoungGun,Yoo, Sang-Sun,Lee, Minjae,Hwang, Keum Cheol,Youngoo, Youngoo Yang,Lee, Kang-Yoon IEEE 2018 IEEE transactions on industrial electronics Vol.65 No.9
<P>In this paper, the design of a signal conditioning analog front-end (AFE) IC for an automotive piezo-resistive type pressure sensor is presented. To improve the pressure-sensing accuracy and compensate for variations in the pressure sensor and signal conditioning IC, gauge factor calibration, digital automatic offset, and gain calibration are proposed and implemented with low power consumption. By using a high-resolution analog-to-digital converter and digital-to-analog converter, the digital automatic calibration circuit can guarantee linearity of output voltage with respect to pressure to within 0.5%. As the analog signal is converted to a digital signal, accuracy in the AFE IC improves. To improve the reliability in the automotive environment, over-voltage and reverse-voltage protection circuits are integrated with the electrostatic discharge protection circuit. Also, electromagnetic interference is reduced by using the proposed spread spectrum clock generator.</P> <P>The proposed design is implemented using 2P4M 0.35 μm CMOS technology with an active area of 1.94 mm × 1.94 mm. Full output ranges from 0.5 to 4.5 V. The ratiometricity error is within ±0.25% when the supply voltage is changed by ±10%. Current consumption is 4.7 mA from a 5 V supply. The output accuracy is within ±0.5% with respect to the PVT variations.</P>
Circularly Polarized Spidron Fractal Dielectric Resonator Antenna
Altaf, Amir,Youngoo Yang,Kang-Yoon Lee,Keum Cheol Hwang IEEE 2015 IEEE antennas and wireless propagation letters Vol.14 No.-
<P>In this letter, a circularly polarized Spidron fractal dielectric resonator antenna is presented. A wide 3-dB axial ratio (AR) bandwidth is realized by merging a Spidron fractal dielectric resonator and a C-shaped slot that can produce circular polarization. The proposed antenna is excited through the coupling between a C-shaped slot in the ground plane and a 50-Ω microstrip feeding line. A prototype of the antenna is fabricated and tested. Reasonable agreement is achieved between the measurement and simulation. The experimental results show that the proposed antenna has a -10- dB reflection bandwidth of 37.29% (4.32-6.30 GHz) and a 3-dB AR bandwidth of 11.57% (5.13-5.76 GHz). The measured gain of the antenna ranges 2.20 dBic to 3.16 dBic within the AR bandwidth.</P>
Analysis and experiments for high-efficiency class-F and inverse class-F power amplifiers
Woo, Young Yun,Yang, Youngoo,Kim, Bumman IEEE 2006 IEEE transactions on microwave theory and techniqu Vol.54 No.5
This paper presents analytic and experimental comparisons for high-efficiency class-F and inverse class-F amplifiers. The analytic formula of the efficiencies, output powers, dc power dissipations, and fundamental load impedances of both amplifiers are derived from the ideal current and voltage waveforms. Based on the formula, the performances are compared with a reasonable condition: fundamental output power levels of class-F and inverse class-F amplifiers are conditioned to be identical. The results show that the inverse class-F amplifier has better efficiency than that of class-F amplifiers as the on-resistance of the transistor increases. For experimental comparison, we have designed and implemented the class-F and inverse class-F amplifiers at I-GHz band using a GaAs MESFET and analyzed the measured performances. Experimental results shows 10% higher power-added efficiency of the inverse class-F amplifier than that of the class-F amplifier, which verifies the waveform analysis.
Wideband Circularly Polarized Spidron Fractal Slot Antenna with an Embedded Patch
Altaf, Amir,Yang, Youngoo,Lee, Kang-Yoon,Hwang, Keum Cheol Hindawi Limited 2017 International journal of antennas and propagation Vol.2017 No.-
<P>In this communication, a wideband circularly polarized (CP) Spidron fractal microstrip antenna is proposed based on the concept of embedded structures. The proposed antenna is excited by a tapered microstrip feedline. A wide 3 dB axial ratio (AR) bandwidth of 28.81% (3.09–4.13 GHz) is obtained by merging the CP bands of the Spidron fractal slot and patch antennas. In addition, a measured −10 dB reflection bandwidth of 47.25% (2.57–4.16 GHz) is reported. The measured results are in reasonable concurrence with the simulated results. The measured gain varies between 2.12 dBic and 3.56 dBic within the AR bandwidth.</P>
Design of 1:4 Ultrawideband Hybrid Transmission-Line Balun
Hwiseob Lee,Wooseok Lee,Youngoo Yang IEEE 2015 IEEE microwave magazine Vol.16 No.1
<P>This article presents the 1:4 wideband balun based on transmission lines that was awarded the first prize in the Wideband Baluns Student Design Competition. The competition was held during the 2014 IEEE Microwave Theory and Techniques Society (MTT-S) International Microwave Symposium (IMS2014). It was initiated in 2011 and is sponsored by the MTT-17 Technical Coordinating Committee. The winner must implement and measure a wideband balun of his or her own design and achieve the highest possible operational frequency from at least 1 MHz (or below) while meeting the following conditions: ? female subminiature version A (SMA) connectors are used to terminate all ports ? a minimum impedance transformation ratio of two ? a maximum voltage standing wave ratio (VSWR) of 2:1 at all ports ? an insertion loss of less than 1 dB ? a common-mode rejection ratio (CMRR) of more than 25 dB ? imbalance of less than 1 dB and 2.5?.</P>
Baseband Noise Reduction Method Using Captured TX Signal for UHF RFID Reader Applications
Sung-Chan Jung,Min-Su Kim,Youngoo Yang IEEE 2012 IEEE transactions on industrial electronics Vol.59 No.1
<P>This paper presents a baseband noise reduction method in the receiver for UHF RFID readers. The signal captured from the transmitter after passing through the main delay components is fed as an LO signal into the down-converter in the receiver. At the down-converter, the LO signal and the leakage signal from the transmitter to the receiver are mixed with each other. The matching of the delay between the two correlated signals virtually eleminates the additional baseband noise included in the phase noises after their mixing. Lowering the baseband noise improves the sensitivity of the receiver, thus allowing the RFID tags to be read further away from the reader. The proposed method was applied to a portable UHF RFID reader for its validation. Compared to the conventional configuration, the simulated baseband noise level of more than 26 dB was reduced by the proposed method. The measured sensitivity of about 19 dB was also improved. As a result, the reading distance was extended by 1.9 m from 2.02 to 3.92 m.</P>