• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.221-224
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• 2005

This paper discribes the nonlinear distortion of a pHEMT power amplifier. In the paper, we have used some commercially available power amplifiers for analyzing the relationship between the $IMD_3$ and ACPR for wireless LAN. And the $IMD_3$ results using two-tone test have been compared with ACPR to satisfy the requited 802.11g standard ACPR value. Measurement result shows that $IMD_3$ of 20MHz tone-spacing need to be more than 18.45dBc for power amplifiers. The WCDMA signal is fed into the power amplifier, for analyzing relationship between the asymmetrical $IMD_3$ and ACLR. With measurement result, the asymmetrical $IMD_3$ characteristic has increased with the increase of two-tone spacing. $IMD_3$ measurement result with maximum 20MHz of the two-tone spacing, shows that the difference between $IMD_3(lower)$ and $IMD_3(upper)$ is about 7dB. And the measured ACLR shows 5dB difference at -4MHz and +4MHz offset from center frequency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.999-1003
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• 2009

We have designed and fabricated a linear drive amplifier with a novel intermodulation distortion(IMD) canceller using $0.18{\mu}m$ CMOS process. The drive amplifier with IMD canceller is composed of a cascode main amplifier and an additional common-source IMD canceller. Since the IMD canceller generates IM3($3^{rd}$-order imtermodulation) signal with $180^{\circ}$ phase difference against the IM3 of the cascode main amplifier, the IM3 power is drastically eliminated. As of the measurement results, $OP_{1dB}$, $OIP_3$, and power-add efficiency are 5.5 dBm, 15.5 dBm, and 21%, respectively. Those are 5 dB, 6 dB, and 13.5% enhanced values compared to a conventional cascode drive amplifier. The IMD3 of the drive amplifier with IMD canceller is enhanced more than 10 dB compared to that of the conventional cascode drive amplifier for input power ranges from -22 to -14 dBm.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.475-477
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• 2005

We simulated 3rd order intermodulation distortion (IMD3) induced Carrier-to-Intermodulation Ratio (CIR) of laser diodes over a wide range of optical modulation index, and compared the results with commercial IMD3 induced CIR specification such as Composite Triple Beat (CTB) of DFB laser transmitter for CATV networks. It shows that the simulation results are in good agreement with the CATV CTB specification within 3dB margin. The results can be used to predict IMD3 induced CIR performance for various analog optical transmission systems with given optical modulation index and the number of transmission channels.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.50-54
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• 2011

In this article, the linearity of single power amplifier is improved by suppress $2^{nd}$ and $3^{rd}$ harmonics at output port of high power amplifier and by cancelling of $3^{rd}$ IMD. The matching network in order to suppress harmonics consists of metamaterial like the CRLH. The $2^{nd}$ and $3^{rd}$ harmonics are suppressed over 27 dBc, respectively. A phase of generated $3^{rd}$ IMD at output of DPA (drive power amplifier) has changed in order to offset the $3^{rd}$ IMD of HPA (high power amplifier). The harmonics of the proposed PAM suppress over 6 dB than single HPA. The PAM has a 36.98 dBm of the output power, 21.6 dB of the power gain and 29.4 % of the PAE. The harmonics is a -53 dBc about PAM. This result indicate that a harmonic level is lower 20 dB than reference power amplifier.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.337-340
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• 2000

In this paper, I compared some characteristics between HPA and LPA using Feedforward method. Feedforward method is known for best IMD correction. HPA generated 46.5㏈c at 45.5㏈m output power. But, using feedforward linearing method, I could improve IMD to 67.17㏈c at the same output power. IMD could be improved 20.67㏈ at 45.5㏈m output power. I measured average power, IMD, total current, and efficiency of two amplifier at many different power levels. I could get about 70d3c IMD using feedforward method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.450-457
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• 2003

In this paper, we studied the effect of asymmetrical 3rd order IMD of power amplifier due to changes in modulation frequency on IMD cancellation performance. The phase extraction method for determining asymmetric rate for phase distortion of IMD is proposed and the phase difference between lower and upper 3rd order IMD is measured by this method. The phase compensation circuit to decrease the phase difference is also designed and fabricated. From the measurement results using the phase compensation circuit applied to 5 W RF power amplifier fur PCS applications, the 3rd order IMD cancellation performance can be achieved up to 2-tone spacing 1.5 MHz (phase difference within 10$^{\circ}$).

• Polymer(Korea)
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• v.36 no.3
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• pp.268-274
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• 2012

The silane coupling agent, 3-(trimethoxysilyl)propyl methacrylate (${\gamma}$-MPTS), was grafted on the surface of alumina nanoparticles. We used the surface modified nanoparticles in the hard coating layer for in-mold decoration (IMD) foils and evaluated the coating properties such as hardness and anti-abrasion property. The effects of electron beam (EB) irradiation on color layer and anchor layer of IMD foils were observed through the difference in color and the cross-cut tape test, respectively. Also, cure kinetics as studied quantitatively under various reaction temperatures by analysis of surface properties and Fourier transform infrared (FTIR) spectroscopy. From these results, we constructed database for the commercial exploitation of EB curing system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.92-96
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• 2003

In this paper, 30 W power Amplifier for IMT-2000 repeater was developed gain flatness and the third IMD (Intermodulation distortion) by Microwave absorber. The absorption ability of the absorber is measured up to -10 ㏈ and -4 ㏈ at 3.6 ㎓, 2.3 ㎓ band respectively. Non using absorber power amplifier has the gain over 57 ㏈, the gain flatness of ${\pm}$0.33 ㏈ and the third IMD of 27 ㏈c at 33.3 W output. Otherwise, using absorber power amplifier has the gain over 58㏈, the gain flatness of less than ${\pm}$0.9, the third IMD over 29 ㏈c at the same output power. As a result, the characteristic of the different type show improvement of 1 ㏈ in gain, 0.3 ㏈ in Gain flatness and 1.77 ㏈c in IMD.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.345-348
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• 2000

In this paper, A Feedforward Linear Power Amplifier for IMT-2000 which IMD characteristics was improved was designed and fabricated. To improve the main power amplifier IMD characteristics, the Feedback loop was added to basic Feedforward Power Amplifier structure. Therefore, the output power of error amplifier can be reduced, and it is easy to control the linearization circuit to cancel total IMD. The designed power amplifier represented the 40㏈m(l0W) output power and -55㏈C 3rd IMD at Center frequency 2.14㎓ (@5㎒).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.943-952
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• 2006

The OFDM system is very good for the high data rate communication system. However, OFDM system has a high PAPR problem. This makes the OFDM signal distorted through the nonlinear HPA(High Power Amplifier). To solve this problem, generally, simple PAPR reduction methods have been considered. However, in this paper, we introduce IMD reduction method instead of PAPR. PAPR is the signal property and the IMD is signal component of the HPA output, which degrades the communication quality. So, instead of PAPR we want to use the IMD reduction method. This is to transmit a signal with the smallest distortion by considering the third order nonlinearity when the data is recovered. We use the TR method that was proposed for the PAPR reduction and we find out the BER performance of two methods. As results, we show that the IMD reduction method improves better BER performance than the PAPR reduction.