• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.140-144
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• 2004

The selectable dual band LNA usually uses common source transistor pair each input of which is selectively driven at a different frequency in a series resonant form. This paper analyzes the degradation in noise figures of the MOSFET common source pair with series resonance when it is driven concurrently at both inputs with different frequencies as a concurrent dual band LNA. Results of analysis will be compared with the measured noise figures of CMOS LNA with double inputs fabricated in 0.18 $\mu\textrm{m}$ CMOS process. Additionally, analyzing the contributions of FET channel noise and source noise from the LNA operating in the other band, this paper proposes optimum matching topology which minimizes the added noises for concurrent operation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.761-767
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• 2007

In this paper, we deal wih a concurrent dual band low noise amplifier for a Radio Frequency Identification(RFID) reader operating at 912MHz and 2.45GHz. The design of the low noise amplifier is based on the TSMC $0.18{\mu}m$ CMOS technology. The chip size is $1.8mm\times1.8mm$. To improve the noise figure of the circuit, SMD components and a bonding wire inductor are applied to input matching. Simulation results show that the 521 parameter is 11.41dB and 9.98dB at 912MHz and 2.45GHz, respectively The noise figure is also determined to 1.25dB and 3.08dB at the same frequencies with a power consumption of 8.95mW.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.499-508
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• 2017

A new digital pre-distortion technique to linearize power amplifier (PA) is proposed for concurrent dual-band transmitters. In the conventional dual-band DPD techniques, two independent dual-feedback paths are required to compensate nonlinear cross-products between different bands as well as the nonlinear self-products of each band's own signal. However, it increases hardware complexity and expense. In this paper, we propose a new DPD method requiring only a single feedback path. In this new structure, the proposed technique first estimates the dual-band PA characteristics using the single feedback path. The DPD parameters are then extracted from the estimated PA characteristics. The DPD performance of the proposed method is validated through computer simulation. According to the results, the proposed technique can achieve comparable performance to the conventional two feedback DPD with significantly reduced hardware complexity.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.168-172
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• 2003

This paper analyzes the output noise and the noise figure of common source MOSFET pair each input of which is separately driven in the different frequencies. This analysis is performed for concurrent dual band cascode CMOS LNA with double inputs and single output fabricated in $0.18{\mu}m$ CMOS process. Since both inputs and output are matched to near $50{\Omega}$ using on-chip inductors, the measured noise figures are much higher than those of usual CMOS LNA. But, the main concern of this paper is focused on the added noise features due to the other channel common source stage. The dual-band LNA results in noise figure of 4.54dB at 2.14GHz and 6.03dB at 5.25GHz for selectable operation and 7.44dB and 6.58dB for concurrent operation. The noise analysis explains why the added noise at each band shows so large difference.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.153-156
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• 2008

본 논문은 Local oscillator의 2차 harmonic 신호를 이용하고 Dual gate FET 형태를 이용한 이중대역 주파수 혼합기 설계에 대한 연구 이다. 기존의 회로 구조는 두 대역을 처리하기 위해 각각 두 개의 국부 발진기와 혼합기를 사용함으로 인하여 구조의 복잡함과 큰 전력 손실이라는 단점을 가지고 있었다. 본 연구는 하나의 주파수 혼합기로 두 개의 대역에서 동시에 적용할 수 있는 Concurrent 이중 대역 설계 연구를 하였다. ISM(Industrial Science Medical) 대역 인 912MHz, 2.45GHz의 RF 입력과 455.5MHz, 1224.5MHz의 LO 입력 신호에서 동일한 IF인 1MHz로 하향변환 했을 때 모의실험 결과 변환이득은 각각 7dB, 12dB로 이고 RF-LO 격리도는 -29dB, -24.7dB가 나왔다. 또한 두 입력 단에서의 반사손실의 -15dB 이상을 얻었다. 또한 각각의 대역에서 잡음지수는 8.5dB, 6.26dB이다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.401-410
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• 2014

This paper presents a high-efficiency concurrent dual-band Class-E power amplifier(PA) that is based on a multi-harmonic matching network(MHMN). The proposed MHMN controls the impedance at 1.3 GHz, 2.1 GHz, and their second and third harmonics, respectively, by using transmission lines only rather than switches or lumped components. The dual-band Class-E PA is implemented using Avago ATF-50189 GaAs p-HEMT. The PA exhibits a measured output power of 27.1 dBm and 25.7 dBm, a power gain of 6.1 dB and 4.7 dB, and a drain efficiency of 71.2 % and 60.1 % at 1.3 GHz and 2.1 GHz, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2615-2618
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• 2009

Double rectangular patch with 4-bridges is investigated for solution of IEEE 802.11b/g (2.4 GHz) and 802.11a (5.5 GHz). Rectangular patch for 5.5 GHz frequency band is printed on the PCB substrate and connected to another rectangular patch for 2.4 GHz frequency band with 4-bridges to obtain dual band operation in an antenna element. 4-bridges can modify the desired frequency band from its original frequency band by changing its width. Gain of 2.4 GHz patch is 5 dBi and 5.5 GHz patch is 3.7 dBi at ${\theta}=0^{\circ}$.