• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.1
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• pp.28-34
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• 2003

In this paper, a predistortion linearizer using series diode is proposed for linearizing the power amplifier in microwave radio systems. The power amplifier should be operated near saturation region to achieve high efficiency. But at this region, amplitude and phase distortions of the amplifier remarkably increase with the increase of input power and cause a significant adjacent channel interference. The linearizer is composed of a series diode with a parallel capacitor, which provides positive amplitude and negative phase deviations with the increasing input power. This type of linearizer using the nonlinearity of diode has improved the C/I(Carrier to Intermodulation Distortion) ratio well. By applying this linearizer to two-tone 880MHz power amplifier, adjacent channel leakage power is improved up to 5dBm.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.501-502
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• 2006

In this paper low power high gain amplifier is suitable for application in low power systems was designed and fabricated. The amplifier used both subthreshold bias for low power and positive feedback Q-enhancement technique for high gain. The amplifier used TSCM $0.18{\mu}m$ RF CMOS technology measures a power gain of 32.3dB, a quality factor of 366 and a power consumption of 3mW in a supply voltage of 1.8V.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.403-408
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• 2008

In this paper, the high efficiency and linearity Doherty power amplifier using DGS and adaptive bias technique has been designed and realized for 2.3GHz WiBro applications. The Doherty amplifier has been implemented us-ing silicon MRF 281 LDMOS FET. The RF performances of the Doherty power amplifier (a combination of a class AB carrier amplifier and a bias-tuned class C peaking amplifier) have been compared with those of a class AB amplifier alone, and conventional Doherty amplifier. The Maximum PAE of designed Doherty power amplifier with DGS and adaptive bias technique has been 36.6% at 34.01dBm output power. The proposed Doherty power amplifier showed an improvement 1dB at output power and 7.6% PAE than a class AB amplifier alone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.978-984
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• 2015

In this paper, we designed a RF transceiver operating up to 200 km operating range and 45 Mbps data rate. The RF transceiver operates in Ku band and composed of up/down converter, high power amplifier, front-end elements. To satisfy the operating range of RF transceiver, 10W power amplifier was required and realized by using GaN power amplifier. Moreover, to mitigate mutual interference for different bandwidth signals due to the adaptive transmission speed control function, SAW filter bank structure was used. To verify system requirement satisfaction AWR simulation tool was used.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.325-328
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• 2000

This paper has been studied a rower amplifier for IMT-2000 handset. Circuit design is performed and optimized by using HP ADS RF software. Designed amplifier consist of 2 stage, has 25㏈ gain, over 27㏈m output power and about 40% power efficiency. Power amplifier operation frequency range is 1955${\pm}$70MHz. Mask layout of the designed Amplifier consisting of 4 mask. The measured results of these values are satisfying the specification of IMT-2000 handset.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.82-86
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• 2010

In this paper, a power amplifier module for WCDMA base-station applications is designed and implemented using GaN field-effect transistors (FETs), which uses an envelope tracking bias system. The designed module consists of an high gain MMIC amplifier, a driver amplifier, a power amplifier, and bias circuits for envelope tracking applications. Especially, a FET bias sequencing circuit and two isolators are integrated for stable RF operations. All circuits are assembled within a single housing, so its dimension is just $17.8{\times}9.8{\times}2.0\;cm3$. Measured results show that the developed power amplifier module has good envelope tracking capability: the power-added efficiency of 35% at the output power range from 30dBm to 40dBm over a wide range of drain bias.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.76-79
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• 2016

This paper describes the successful development and the performance of X-band 50 W pulsed power amplifier using a 50 W GaN-on-SiC high electron mobility transistor. The GaN HEMT with a gate length of $0.25{\mu}m$ and a total gate width of 12 mm were fabricated. The X-band pulsed power amplifier exhibited an output power of 50 W with a power gain of 6 dB in a frequency range of 9.2~9.5 GHz. It also shows a maximum output power density of 4.16 W/mm. This 50 W GaN HEMT and X-band 50 W pulsed power amplifier are suitable for the radar systems and related applications in X-band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.117-122
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• 2016

In this paper, we propose 24-GHz CMOS radio frequency (RF) power amplifier for short-range automotive collision avoidance radars. This circuit contains common source stage with inter-stages conjugate matching circuit as a class-A mode amplifier. The proposed circuit is designed using TSMC $0.13-{\mu}m$ mixed signal/RF CMOS process ($f_T/f_{MAX}=120/140GHz$). It operates at the supply voltage of 2V, and it is designed to have high power gain, low insertion loss and low noise figure in the low supply voltage. To reduce total chip area, the circuit used transmission lines instead of the bulky real inductor. The designed CMOS power amplifier showed the smallest chip size of $0.1mm^2$, the lowest power consumption of 40mW, the highest power gain of 26.5dB, the highest saturated output power of 19.2dBm and the highest maximum power-added efficiency of 17.2% as compared to recently reported results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.87-92
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• 2005

In this paper, adaptive bias circuit and PBG structure have been employed to suppress IMD and improve PAE (Power Added Efficiency) of the power amplifier. It is controlling the gate 'dc' bias voltage with the envelope of the input RF signal. and The PBG structure has been employed on the output port of power amplifier . The proposed power amplifier using adaptive bias circuit and PBG has been improved the IMG by 3 dBc, and the average PAE by $35.54\%$, respectively.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.31-33
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• 2003

Power amplifier linearity plays a major role in the design of RF communication systems. In this paper, predistortion type linearizer was designed an independently controllable AM/AM and AM/PM predistortion linearizers. This linearizer allows independent adjustment of the AM/AM and AM/PM curves by using two adjustable voltages to compensate the power amplifier non-linearities. The predistortion linearizer was improved the ACPR by 6dB with cdma2000 multi carrier signals. Applying this linearizer to two-tone 880MHz power amplifier, an improvement of adjacent channel leakage power up to 5dBm has been achieved.