• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.10a
• /
• pp.469-471
• /
• 2022

This paper presents an implementation of a calibration circuit to correct the gain error, DC offset and sampling clock phase error generated in the process of converting digital pixels to analog pixels to drive an analog-driven 4K UHD LCOS panel. The proposed calibration circuit consists of a gain and DC offset adjustment circuit and a sampling clock phase adjustment circuit. The calibration circuit is implemented with an FPGA device, and video amplifiers.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.4
• /
• pp.77-82
• /
• 2017

As frequencies increase to the millimeter wave bands the cross sections of wave guides become smaller than a few millimeters, which cause sapatial problems in realization of spatial combining power amplifiers. In this paper we intented to overcome the problem by widening the width of wave guides using horn antenna principles. We designed a widened rectangular wave guide for using in spatial combining power amplifier in 60GHz ISM band(57-64GHz), and we installed Antipodal transition in the widened wave guide, and then we characterized it as a spatial combining power amplifier. For the compatibility of WR15 standard wave guide, we widened the width of WR15 to 7mm using principle of H-plane sectoral horn antenna and then installed 3 slots of back to back Antipodal transition. The designed spatial combining power amplifier showed good characteristics of return loss less than -22.4dB and insertion loss less than 0.53dB. However, as widening the width of the wave guide, additional modes such as $TE_{20}$, $TE_{30}$ in addition to $TE_{10}$ were accurred in the bandwidth of WR15, which restricted the bandwidth and widening of the width of the wave guide.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.8
• /
• pp.105-111
• /
• 2004

In this paper, millimeter-wave high gain and broadband MHEMT cascode amplifiers were designed and fabricated. The 0.1 ${\mu}{\textrm}{m}$ InGaAs/InAlAs/GaAs Metamorphic HEMT was fabricated for cascode amplifiers. The DC characteristics of MHEMT are 640 mA/mm of drain current density, 653 mS/mm of maximum transconductance. The current gain cut-off frequency(f$_{T}$) is 173 GHz and the maximum oscillation frequency(f$_{max}$) is 271 GHz. By using the CPW transmission line, the cascode amplifier was designed the matched circuit for getting the broadband characteristics. The designed amplifier was fabricated by the MHEMT MIMIC process that was developed through this research. As the results of measurement, the 1 stage amplifier obtained 3 dB bandwidth of 37 GHz between 31.3 to 68.3 GHz. Also, this amplifier represents the S21 gain with the average 9.7 dB gain in bandwidth and the maximum gain of 11.3 dB at 40 GHz. The 2 stage amplifier has the broadband characteristics with 3 dB bandwidth of 29.5 GHz in the frequency range from 32.5 to 62.0 GHz. The 2 stage cascode amplifier represents the high gain characteristics with the average gain of 20.4 dB in bandwidth and the maximum gain of 22.3 dB at 36.5 GHz.z.z.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.4
• /
• pp.381-391
• /
• 2010

In this paper, a novel frequency reconfigurable active array antenna(RAA) system, which can be reconfigurable for three reconfigurable frequency bands, is proposed by using commercial RF MEMS switches. The MEMS switch shows excellent insertion loss, linearity, as well as isolation. So, the system performance degradation of the reconfigurable system by using MEMS switches can be minimized. The proposed frequency reconfigurable active antenna system is consisted with the noble frequency reconfigurable front-end amplifiers(RFA) with the simple reconfigurable impedance matching circuits(RMC), reconfigurable antenna elements(RAE), as well as a reconfiguration control board(RCB) for MEMS switch control. The proposed RAA system can be reconfigurable for three frequency bands, 850 MHz, 1.9 GHz, and 3.4 GHz, with $2{\times}2$ array of the RAE having broadband printed dipole antenna topology. The validity of the proposed RFA as well as RAA is also presented with the experimental results of the fabricated systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.1
• /
• pp.53-61
• /
• 2014

In this paper, we present the design, fabrication and measurement of high efficiency GaN HEMT power amplifier using harmonic matching technique. In order to achieve high efficiency, harmonic load-pull simulation is performed, that is, the optimum load impedances are determined at $2^{nd}$ and $3^{rd}$ harmonic frequencies as well as at the fundamental. Then, the output matching circuit is designed based on harmonic load-pull simulation. The measurement of the fabricated power amplifier shows the linear gain of 20 dB and $P_{1dB}$(1 dB gain compression point) of 33.7 dBm at 1.85 GHz. The maximum power added efficiency(PAE) of 80.9 % is achieved at the output power of 38.6 dBm, which belongs to best efficiency performance among the reported high efficiency power amplifiers. For W-CDMA input signal, the power amplifier shows a PAE of 27.8 % at the average output power of 28.4 dBm, where an ACLR (Adjacent Channel Leakage Ratio) is measured to be -38.8 dBc. Digital predistortion using polynomial fitting was implemented to linearize the power amplifiers, which allowed about 6.2 dB improvement of an ACLR performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.8
• /
• pp.754-763
• /
• 2002

This paper discusses the improved power performances of the size-reduced amplifier using defected ground structure (DGS). The slow-wave effect and enlarged electrical length occur due to the additional equivalent circuit elements of DGS. Using these properties, it is possible to reduce the length of transmission lines in order to keep the same original electrical lengths by inserting DGS on the ground plane. The matching and performances of the amplifier are preserved even after DGS patterns have been inserted. While there is no loss in the size-reduced transmission lines at the operating frequency, but there exists loss to some extent at harmonic frequencies. This leads to the more excellent inherent capability of harmonic rejection of the size-reduced amplifier. Therefore, it is expected tile harmonics of the size-reduced amplifier are smaller than those of the original amplifier. The measured second harmonic, third order intermodulation distortion (IMD3), and adjacent channel power ratio (ACPR) of the size-reduced amplifier are smaller than those of the original amplifier by 5 dB, 2~6 dB, and 1~4 dB, respectively, as expectation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.695-700
• /
• 2018

This paper presents the development of compact and lightweight broadband power amplifier module using HMIC (Hybrid Microwave Integrated Circuit) technology that could be high-density integration for many non-packaged microwave components into the small area of a high dielectric constant printed circuit board, such as a ceramic substrate, also using the special design and fabrication schemes for the structure of minimized electromagnetic interference to obtain the homogeneous electrical performance at the wideband frequency. The results confirmed that the small signal gain has a gain flatness of ${\pm}1.5dB$ within the range of 32 to 36 dB. In addition, the output power satisfied more than 30 dBm. The noise figure was measured within 7 dB, and OIP3 (Output Third Order Intercept Point) was more than 39 dBm. The fabricated broadband power amplifier satisfied the target specification required to electrically drive the high power amplifiers of jamming generators for electronic warfare, so the actual applicability to the system was verified. Future studies will be aimed at designing other similar microwave power amplifiers in the future.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.5
• /
• pp.646-654
• /
• 2020

This paper is to develop an electromagnetic wave-based sensor that can measure the spatial distribution of precipitation, and to a electromagnetic wave rain gauge (hereinafter, "EWRG") capable of simultaneously measuring rainfall, snowfall, and wind field, which are the core of heavy rain observation. Through this study, the LFM transmission and reception signals were theoretically analyzed. In addition, In order to develop a radar transceiver, LFM transceiver design and simulation were conducted. In this paper, we developed a K-BAND pulse-driven 6W SSPA(Solid State Power Amplifiers) transceiver using a small HMIC(Hybrid Microwave Integrated Circuit). It has more than 6W of output power and less than 5dB of receiving NF(Noise Figure) with short duty of 1% in high temperature environment of 65 degrees. The manufactured module emits LFM and Square Pulse waveform with the built-in waveform generator, and the receiver has more than 40dB of gain. The transceiver developed in this paper can be applied to the other small weather radar.

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.5
• /
• pp.507-517
• /
• 2022

The PhotoAcoustic Microscopy (PAM) has been proved to be a useful tool for biological and medical applications due to its high spatial and contrast resolution. PAM is based on transmission of laser pulses and reception of PA signals. Since the strength of PA signals is generally low, not only are high-performance optical and acoustic modules required, but high-performance electronics for imaging are also particularly needed for high-quality PAM imaging. Most PAM systems are implemented with a combination of several pieces of equipment commercially available to receive, amplify, enhance, and digitize PA signals. To this end, PAM systems are inevitably bulky and not optimal because general purpose equipment is used. This paper reports a PA signal receiving system recently developed to attain the capability of improved Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of PAM images; the main module of this system is a low noise, wideband signal receiver that consists of two low-noise amplifiers, two variable gain amplifiers, analog filters, an Analog to Digital Converter (ADC), and control logic. From phantom imaging experiments, it was found that the developed system can improve SNR by 6.7 dB and CNR by 3 dB, compared to a combination of several pieces of commercially available equipment.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.4 no.4
• /
• pp.293-299
• /
• 2004

An active RC 2nd order Butterworth filter suitable for a baseband channel-selection filter of a direct conversion receiver is presented. The linearity of the 2nd order Butterworth filter is analyzed. In order to improve the linearity of the filter, the operational amplifiers should have a high linear gain and low 3rd harmonic, and the filter should be designed to have large feedback factor. This second order Butterworth filter achieves-14dBV in-channel (400kHz, 500kHz) IIP3, +29dBV out-channel (10MHz, 20.2MHz) IIP3 and 15.6 $nV/\sqrt{Hz}$ input-referred noise and dissipates 10.8mW from a 2.7-V supply. The analysis and experimental results are in good agreement