• ETRI Journal
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• v.33 no.5
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• pp.679-688
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• 2011

A new discrete-amplitude pulse width modulation (DAPWM) scheme for a high-efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low-frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching-mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.851-856
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• 2010

This paper presents an efficiency enhancement for the balanced power amplifier using DBS(Dynamic Bias Switching) method which dynamically provides the power amplifier with two bias voltage levels according to the input envelope signal. In order to apply the dynamic biases to each side of the balanced power amplifier, two switching stages are adopted. Using an OFDM signal with a bandwidth of 20 MHz and a PAR(Peak to Average Ratio) of 8.5 dB, 6 % of PAE(Power-Added Efficiency) is improved at an output power of 42.5 dBm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.7-12
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• 2008

In this paper, a highly efficiency power amplifier is presented for multi-band antenna system. The class F power amplifier operating in dual-band designed with one LDMOSFET. An operating frequency of power amplifier is 900 MHz and 2.14 GHz respectively Matching networks and harmonic control circuits of amplifier are designed by using the unit cell of composite right/left-handed(CRLH) transmission line(TL) realized with lumped elements. The CRLH TL can lead to metamaterial transmission line with the dual-band holing capability. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Because the control of all harmonic components for high efficiency is very difficult, we have controled only the second- and third-harmonics to obtain the high efficiency with the CRLH TL. Also, the proposed power amplifier has been realized by using the harmonic control circuit for not only the output matching network, but also the input matching network for better efficiency.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.209-215
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• 2003

In this paper. We tested and fabricated the error amplifier for the 15 Watt linear power amplifier for the IMT-2000 baseband station. The error amplifier was comprised of subtractor for detecting intermodulation distortion, variable attenuator for control amplitude, variable phase shifter for control phase, low power amplifier and high power amplifier. This component was designed on the RO4350 substrate and integrated the aluminum case with active biasing circuit. For suppression of spurious, the through capacitance was used. The characteristics of error amplifier measured up to 45 dB gain, $\pm$0.66 dB gain flatness and -15 dB input return loss. Results of application to the 15 Watt feedforward Linear Power Amplifier, the error amplifier improved with 27 dB cancellation from 34 dBc to 61 dBc IM$_3$.

• ETRI Journal
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• v.36 no.3
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• pp.498-501
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• 2014

A C-band 50 W high-power microwave monolithic integrated circuit amplifier for use in a phased-array radar system was designed and fabricated using commercial $0.25{\mu}m$ AlGaN/GaN technology. This two-stage amplifier can achieve a saturated output power of 50 W with higher than 35% power-added efficiency and 22 dB small-signal gain over a frequency range of 5.5 GHz to 6.2 GHz. With a compact $14.82mm^2$ chip area, an output power density of $3.2W/mm^2$ is demonstrated.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.851-854
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• 1999

A high efficient, CMOS RF power amplifier at a 2.SV power supply for the band of 902-928MHz was designed and analyzed in 0.25${\mu}{\textrm}{m}$ standard CMOS technology. The output power of designed amplifier is being digitally controlled from a minimum of 2㎽ to a maximum of 21㎽, corresponding to a dynamic range of l0㏈ power control. The frequency response of this power amplifier is centered roughly at 915MHz. The power added efficiency of designed amplifer is almost 48% at maximum output power of 21㎽.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.195-198
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• 2000

A CMOS power amplifier for wireless home networks is designed using 0.2sum 1-poly 5-metal standard CMOS technology and simulation results are presented. The power amplifier provides maximum output power of 16.5dBm to a 50-Ohm load at 2.450Hz and dissipates 220mW of dc power from a single 2.5-V supply. The designed CMOS power amplifier has power control range of 20dB and an overall power-added efficiency of 17%

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.2
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• pp.51-59
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• 2010

In this paper, we propose an inverted type asymmetric Doherty amplifier with optimized efficiency characteristic in wanted output power back-off (OPBO) range according to peak to average power ratio of input signal In order to obtain optimized efficiency of the asymmetric Doherty amplifier in wanted OPBO, peak power ratio between main amplifier and peaking amplifier was determined and then impedance of 90 degrees impedance transformer was obtained by peak power ratio. The offset line length and peak dividing ratio of the asymmetric Doherty amplifier were also calculated. From the measurement results, the proposed amplifier has achieved 40 % drain efficiency and -35 dBc adjacent channel leakage ratio at the average output power of 48.7 dBm for CDMA 2000 1x 3-FA test signal.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.50-54
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• 2011

In this article, the linearity of single power amplifier is improved by suppress $2^{nd}$ and $3^{rd}$ harmonics at output port of high power amplifier and by cancelling of $3^{rd}$ IMD. The matching network in order to suppress harmonics consists of metamaterial like the CRLH. The $2^{nd}$ and $3^{rd}$ harmonics are suppressed over 27 dBc, respectively. A phase of generated $3^{rd}$ IMD at output of DPA (drive power amplifier) has changed in order to offset the $3^{rd}$ IMD of HPA (high power amplifier). The harmonics of the proposed PAM suppress over 6 dB than single HPA. The PAM has a 36.98 dBm of the output power, 21.6 dB of the power gain and 29.4 % of the PAE. The harmonics is a -53 dBc about PAM. This result indicate that a harmonic level is lower 20 dB than reference power amplifier.

• Journal of IKEEE
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• v.23 no.1
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• pp.181-187
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• 2019

In this paper, we demonstrated a power amplifier monolithic microwave integrated circuit (MMIC) for X-band radar applications. It utilizes commercial $0.25{\mu}m$ GaN-based high electron mobility transistor (HEMT) technology and delivers more than 20 W of output power. The developed GaN-based power amplifier MMIC has small signal gain of over 22 dB and saturated output power of over 43.3 dBm (21.38 W) in a pulse operation mode with pulse width of $200{\mu}s$ and duty cycle of 4% over the entire band of 9 to 10 GHz. The chip dimensions are $3.5mm{\times}2.3mm$, generating the output power density of $2.71W/mm^2$. Its power added efficiency (PAE) is 42.6-50.7% in the frequency bandwidth from 9 to 10 GHz. The developed GaN-based power amplifier MMIC is expected to be applied in a variety of X-band radar applications.