• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.372-376
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• 2004

Digital memory circuits have been developed very fast according to the progress of semiconductor technology But It was very difficult to memorize a high frequency radio signal. Many years ago an analog loop was used for store of radio frequency signal, and the digital radio frequency memory was made to the development of wideband amplifier and high speed sampler. We present a design of wide-band DRFM using Johnson code and the simulation results with respect to the sampling speed. in this paper.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.264-272
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• 2009

In this paper, a Ka-band 10 W power amplifier module is designed and fabricated using MIC(Microwave Integrated Circuit) module technology which combines multiple power MMIC(Monolithic Microwave Integrated Circuit) chips on a thin film substrate. Modified Wilkinson power dividers/combiners are used for millimeter wave modules and CBFGC-PW-Microstrip transitions are utilized for reducing connection loss and suppressing resonance in the high-gain and high-power modules. The power amplifier module consists of seven MMIC chips and operates in a pulsed mode. for the pulsed mode operation, a gate pulse control circuit supplying the control voltage pulses to MMIC chips is designed and applied. The fabricated power amplifier module shows a power gain of about 58 dB and a saturated output power of 39.6 dBm at a center frequency of the interested frequency band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.162-172
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• 2011

In this paper, a design and fabrication of 4 W power amplifier for the WiMAX frequency band(2.3~2.7 GHz) are presented. The adopted active device is a commercially available GaN HEMT chip of Triquint Company, which is recently released. The optimum input and output impedances are extracted for power amplifier design using a specially self-designed tuning jig. Using the adopted impedances value, class-F power amplifier was designed based on EM simulation. For integration and matching in the small package module, spiral inductors and interdigital capacitors are used. The fabricated power amplifier with $4.4{\times}4.4\;mm^2$ shows the efficiency above 50 % and harmonic suppression above 40 dBc for second(2nd) and third(3rd) harmonic at the output power of 36 dBm.

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.176-182
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• 2010

This paper proposes that an inverse class-E amplifier is used a tunable parallel resonator at output port in order to maintain a high power-added efficiency(PAE) and output power with wide frequency ranges. A tunable circuit has a constant Q factor at operating frequency ranges and because of using varactor diode, the inductor and capacitor values of resonator can be changed. Also, the inductance value for zero-current switching (ZCS) is implemented a lumped element and the capacitance value is made a distributed element for phase compensation. The inverse class E amplifier using tunable parallel resonator is obtained to deliver 25dBm output power and achieve maximum power added efficiency(PAE) of 75% at 65-120MHz frequency ranges.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.154-157
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• 2008

A class-E RF(Radio Frequency) power amplifier for wireless application is designed using standard CMOS technology. To drive the class-E power amplifier, a class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. The reliability characteristic is improved when a finite-DC feed inductor is used instead of an RF choke with the load. After one year of operating, when the load is an RF choke the output current and voltage of the power amplifier decrease about 17% compared to initial values. But when the load is a finite DC-feed inductor the output current and voltage decrease 9.7%. The S-parameter such as input reflection coefficient(S11) and the forward transmission scattering parameter(S21) is simulated with the stress time. In a finite DC-feed inductor the characteristics of S-parameter are changed slightly compared to an RF-choke inductor. From the simulation results, the class-E power amplifier with a finite DC-feed inductor shows superior reliability characteristics compared to power amplifier using an RF choke.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.9-15
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• 2015

A CMOS band-pass delta-sigma modulator(BPDSM) and cascode class-E power amplifier have been developed CMOS for Class-S power amplifier applications. The BPDSM is operating at 1-GHz sampling frequency, which converts a 250-MHz sinusoidal signal to a pulse-width modulated digital signal without the quantization noise. The BPDSM shows a 25-dB SQNR(Signal to Quantization Noise Ratio) and consumes a power of 24 mW at an 1.2-V supply voltage. The class-E power amplifier exhibits an 18.1 dBm of the maximum output power with a 25% drain efficiency at a 3.3-V supply voltage. The BPDSM and class-E PA were fabricated in the Dongbu's 110-nm CMOS process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.6 s.109
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• pp.538-545
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• 2006

In this paper, an asymmetric high power extended Doherty amplifier for WCDMA base-station applications is presented. The amplifier has an extended peak efficiency over 9 dB of output power and a linear dynamic range characteristic. To realize the peak efficiency extension and linear dynamic range characteristic, a two times larger peaking device compared to the main device, and an unequal power divider are used. From the experimental results of 1FA WCDMA signal, this amplifier has an efficiency of 31 % and an ACLR of -35 dBc is achieved at 9 dB back-off from P1 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.852-859
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• 2006

This paper suggests a developing approach of EHF TWTA for satellite communications. In order to improve RF performance and gain, we design and realize an EHF TWTA using a linearizer and drive amplifiers. Through the embodiment and experiment of 80 W EHF TWTA, this method satisfies the design specifications. Therefore, this approach is very useful and can be used to develop the similar equipments.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.96-99
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• 2003

This paper presents the development of a Ku-band Low Noise Amplifier with the Noise figure of 1.4dBmax, the gain of 35dB, and the In/Out Return toss of -22dB/-18dB in the frequency range from 14 to 14.5GHz for Satellite transponders. All RF components were assembled using a hybrid technology with 15-mil thin-film substrates. The mechanical and thermal design of the housing was performed considering a vibration and a vacuum of space environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.493-499
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• 2011

To improve the bandwidth efficiency of conventional orthogonal modulation, the MCTO(Multi-Code Trans-Orthogonal) modulation, which is modified orthogonal modulation, was proposed. However, the RF(Radio Frequency) power amplifier for the MCTO modulation is too complex to reject the amplitude distortion due to the non-constant amplitude property of the MCTO. Therefore, in this paper, CAMCTO(constant-amplitude multi-code trans-orthogonal) modulation is proposed by using the constant-amplitude encoding algorithm for multi-code signal. Additionally, the performance of the proposed CAMCTO modulation is compared with those of the orthogonal modulation and the MCTO modulation by using the computer simulation. The computer simulations show that the bandwidth efficiency of the proposed CAMCTO modulation is better than that of the conventional orthogonal modulation.