• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.241-247
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• 2016

This paper proposes the design and measurement of a 6-18 GHz front-end receiver module that has been combined into a one- channel output from a two-channel input for electronic warfare support measures (ESM) applications. This module includes a limiter, high-pass filter (HPF), power combiner, equalizer and amplifier. This paper focuses on the design aspects of reducing the noise figure (NF) and matching the phase and amplitude. The NF, linear equalizer, power divider, and HPF were considered in the design. A broadband receiver based on a combined configuration used to obtain low NF. We verify that our receiver module improves the noise figure by as much as 0.78 dB over measured data with a maximum of 5.54 dB over a 6-18 GHz bandwidth; the difference value of phase matching is within $7^{\circ}$ between ports.

• Journal of electromagnetic engineering and science
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• v.11 no.1
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• pp.16-26
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• 2011

This paper presents high power and high efficiency Doherty amplifiers for 2.345 GHz wireless broadband (WiBro) applications that use a Nitronex 125-W ($P_{3dB}$) GaN high electron mobility transistor (HEMT). Two- and three-way Doherty amplifiers and a saturated Doherty amplifier using Class-F circuitry are implemented. The measured result for a center frequency of 2.345 GHz shows that the two-way Doherty amplifier attains a high $P_{3dB}$ of 51.5 dBm, a gain of 12.5 dB, and a power-added efficiency (PAE) improvement of about 16 % compared to a single class AB amplifier at 6-dB back-off power region from $P_{3dB}$. For a WiBro OFDMA signal, the Doherty amplifier provides an adjacent channel leakage ratio (ACLR) at 4.77 MHz offset that is -33 dBc at an output power of 42 dBm, which is a 9.5 dB back-off power region from $P_{3dB}$. By employing a digital pre-distortion (DPD) technique, the ACLR of the Doherty amplifier is improved from -33 dBc to -48 dBc. The measured result for the same frequency shows that the three-way Doherty amplifier, which has a $P_{3dB}$ of 53.16 dBm and a gain of 10.3 dB, and the saturated Doherty amplifier, which has a $P_{3dB}$ of 51.1 dBm and a gain of 10.3 dB, provide a PAE improvement of 11 % at the 9-dB back-off power region and 7.5 % at the 6-dB back-off region, respectively, compared to the two-way Doherty amplifier.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.610-612
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• 2013

A novel balanced distributed amplifier (DA) was proposed using novel impedance transforming MEMS baluns. The impedance transforming MEMS balun is matched to $50{\Omega}$ at one input port and $25{\Omega}$ at two output ports. It is based on the electric field mode-change method, thus it is strongly independent of frequency and very compact. The novel balanced DA consists of two $25{\Omega}$-matched DAs and these are combined by $50{\Omega}$-to-$25{\Omega}$ baluns. Theoretically, it has two times wider bandwidth and power capability than the conventional DA. So as to verify the proposed concept, we designed and fabricated a conventional DA and the proposed one using 0.15-${\mu}m$ GaAs pHEMT technology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1038-1044
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• 2011

In this paper, the multichannel intermediate frequency transceiver for broadband multimedia system is designed and the experimental results are analyzed. Basic elements of the transceiver such as frequency synthesizer, amplifier, mixer, automatic gain control amplifier are introduced. The analysis technique described here applies not only to amplifier but also to any other nonlinear components such as mixers and frequency doubler. Through the investigation of the power spectrum density of the transmitted signal, the phase noise of the local oscillator is evaluated below 70 dBc/kHz. The frequency characteristics of the modulated signal is flat within the system bandwidth. Also the effects of adjacent channel interference and supurious emission are analyzed. And the function of automatic gain control amplifier is well operated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.840-845
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• 2013

In this paper, the broadband frequency double down-converter based on LC filter technologies has been designed and implemented, and its performances are introduced. The Designed frequency double down-converter is consisted with a low-noise amplifier, mixer, IF amplifier, LC filter, DC-block capacitor and RF-bypass capacitor. Especially, instead of active devices of a typical converter, the suggested converter designed using passive devices to provide both low-power consumption and low-cost model. As results of the measurement, the implemented frequency double down-converter realizes the broadband performance with the bandwidth of 100MHz (13~113MHz) at the center frequency of 63MHz, and its gain is approximately 40dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.634-639
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• 2006

In this paper an MMIC 2-stage power amplifier is designed and fabricated for 5GHz wireless LAN applications using $0.5{\mu}m$ gate length PHEMT transistors. The PHEMT gate width is optimized in order to meet the linearity and efficiency of the MMIC power amplifier. The $0.5{\mu}m\times600{\mu}m$ PHEMT for the drive stage and $0.5{\mu}m\times3000{\mu}m$ PHEMT for the amplification stage are the optimized sizes to achieve more than 25dBc of third order IMD at the power level of 3dB back-off from the input P1dB and more than 22dBm output power under a supply voltage of 3.3V. The two-stage MMIC power amplifier is designed to be used for the both of HIPERLAN/2 and IEEE 802.11a because of its broadband characteristics. The fabricated PHEMT MMIC power amplifier exhibits a 20.1dB linear power gain, a maximum 22dBm output power, a 24% power added efficiency under 3.3V supply voltage. The input and output on-chip matching circuits are included on a chip of $1400\times1200{\mu}m^2$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.497-502
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• 2007

Broadband monolithic SiGe HBT variable gain amplifier with a feedforward configuration have been newly developed to improve bandwidth and dB-linearly controlled gain characteristics. The VGA has been implemented in a $0.35-{\mu}m$ BiCMOS process. The VGA achieves a dynamic gain-control range of 19.6 dB and a 3-dB bandwidth of 4 GHz ($4{\sim}8\;GHz$) with the control-voltage range from 0.6 to 2.6 V. The VGA produces a maximum gain of 9.3 dB at 6 GHz and a output power of -3 dBm at 8 GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.9
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• pp.1027-1034
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• 2014

We present the Low Power Broadband Low noise amplifier(LNA) that can be applied a whole bandwidth from 3G to 4G LTE. This multi input LNA was designed to steadily amplify through a multi input method regardless the size of the input signal and operate on a wide range of frequency band from a standard 3G CDMA band 1.2GHz to LTE band 2.5GHz. The designed LNA consumes an average of 6mA on a 1.2V power supply and this was affirmed using computer simulation tests. The amplification which was corresponded to the lowest input signal is at a maximum of 20dB and was able to obtain the minimum value of the gain of -10dB. The Noise figure is less than 3dB at a High-gain mode and is less than 15dB at a Low-gain mode.

• International Journal of Contents
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• v.2 no.1
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• pp.29-33
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• 2006

The common-source low noise amplifier(LNA) with inductive degeneration using a genetic algorithm is designed and tested for a down converter in an industrial, scientific and medical (ISM) band application and a wireless broadband internet service (WiBro). The genetic algorithm optimizes the reflection coefficients to be well matched the input and output ports between multistage transistor amplifiers, and it generates low voltage standing wave ratio as well as gain flatness of the amplifier. The stability and the gain flatness of the LNA have been improved by combining the matching circuits and the series feedback microstrip lines with inductive degeneration at common-source port. In the frequency range of ISM band and WiBro application operating at $2.3GHz{\sim}2.5GHz$, the measured power gain and maximum voltage standing wave ratio (VSWR) of the LNA are $41{\pm}0.5dB$ and 1.3, and the noise figure of the LNA is lower than 0.85dB. The above results are agreed well with the theoretical values of the amplifiers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.693-695
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• 2015

The design and implementation of a broadband and linear HPA for TVWS are presented in this paper. The spectrum mask and transmitted power of HPAs for TVWS must be controlled and meet the regulations to minimize interference effects on the present broadcasting systems. The implemented HPA has the operating frequency of 470 ~ 698MHz with the maximum 48.63dB and minimum 43.45dB gain, input reflection coefficient of below -21.32dB, output reflection coefficient of below -4.29dB and the linearity of -45.24dBc at 28.79dBm output power.