• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.1
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• pp.40-46
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• 1974

This paper deals with the self-excited mixer using tunnel diode oscillator operated as a microwave source and Doppler signal detector. The system impedance, the oscillation condition and the frequency conversion theory including moving target are investigated. The oscillating frequency and the output of tunnel diode oscillator are 2.035 GHz and 0.1 mW. The input signal frequency which is equivalent to Doppler signal is lower than tunnel diode oscillator frequency by 125 MHz. TDe conversion loss has been investigated as a functicn of input signal level. This loss is greater than 67 db for the large pump mode.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.69-72
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• 2013

In long-range ultrasonic testing, a phased array probe composed of multiple identical transducers with an uniform interval of one quarter wavelength is usually used for the transmission or reception directivity control. This paper shows that the propagation directions of individual echoes can be identified in real time by displaying the inputs of a process for summing the constitution reception signals after compensating the phase difference due to the transducer interval, together with the output of the process. A constructive interference of the constitution echoes indicates a forward direction echo propagating along an intended direction while a destructive interference implies a reverse direction echo propagating along the direction opposite to the intended one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1484-1491
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• 2020

Since the slot line transmits electric and magnetic signals through the slot, the size of the slot greatly affects the signal power loss. In order to have low loss, the slot line is mainly used at a high frequency of above 3GHz on a substrate having a high dielectric constant(er). This paper proposes the 4:1 impedance transformer using a slot line on TLC-30 laminate (h=20mil, er=3.0; Taconic) being a relatively low dielectric constant at a frequency of 1.85GHz. In the proposed impedance transformer, the dielectric resonator is arranged on the slot line to reduce signal loss occurring at the slot line. The proposed 4:1 microstrip-slot line impedance transformer fabricated using a (Zr,Sn)TiO4 dielectric resonator(er=38) has the transmission loss(S21) of -0.375dB and the reflection value(S11) of -27.6dB at 1.855GHz. This confirms that the slot line can be stably used even in a low dielectric constant substrate and a low frequency region by using a dielectric resonator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.480-485
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• 2004

In this paper, a new predistortion linearizing method using frequency up-conversion operation of mixer is proposed. This linearizing method doesn't require any additional signal sources in spite of frequency up-conversion mixing operation. This method extracts the 2nd low frequency intermodulation distortion signal from input signals and uses the extracted 2nd low frequency intermodulation distortion signal as mixing signal source. To show validation of the proposed predistortion method, we made K-PCS power amplifier. On 2-tone signals amplification process, the (C/I) ratio of amplifier is improved 26 ㏈ (@Po=22 ㏈m/tone), where two tones are 1.8544 ㎓ and 1.8556 ㎓, respectively. And (C/I) ratio is improved more than to 20 ㏈ for 17 ㏈ output signal dynamic range. On IS-95A CDMA 1FA amplification process, the improvements of adjacent channel power ratio(ACPR) are 10.8 ㏈ and 6.4 ㏈ at ${\pm}$885 ㎑ and ${\pm}$1.25 ㎒ offset points, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.141-147
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• 2008

This paper describes the design of frequency down converting Mixer in the receiver to use compound semiconductor and CMOS product process. The basic theory and structure of frequency down converting Mixer is surveyed, and we design mixer circuit with active balun which use the compound semiconductor and CMOS process. This mixer convert a single ended signal to differential signal at input port of RF and LO instead of matching circuit to get dual band balanced mixer structure and characteristic broadband. This designed mixer has a conversion gain $-1{\sim}-6[dB]$ at $2{\sim}6[GHz]$ bandwidths. However, the simulation of the designed mixer with active balun has the result of a 7[dB] conversion gain for -2[dBm] LO input power and -10[dBm] input P1[dB] at 5.8[GHz].

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.365-367
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• 2013

본 논문에서는 $0.18{\mu}m$ CMOS 공정 기술을 이용하여 12-bit 1MSps 연속 근사화 아날로그-디지털 변환기(Analog to Digital Converter : ADC)를 설계하였다. 설계된 아날로그-디지털 변환기는 Cadence Tool을 이용하여 시뮬레이션 및 레이아웃을 진행하였다. 시뮬레이션 결과 1.8V의 공급전압에서 전력 소모는 5.5mW였고, 입력 신호의 주파수가 100kHz일 때, SNDR은 70.03dB, 유효 비트수는 11.34bit의 결과를 보였다. 설계된 변환기는 $0.8mm{\times}0.7mm$ 크기로 레이아웃 되었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1053-1058
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• 2021

This paper presents the multi-band mixer which converts a X-, K- and Ka-band adaptively by adjusting the gate-bias voltage of an active device. The proposed mixer presented a conversion loss of -10 dB at -0.8 V gate-bias voltage for X-band, a conversion loss of -9 dB at -0.3 V gate-bias voltage for K-band and for Ka-band, a conversion loss of -7 dB at -0.2 V gate-bias voltage under the LO power of +6.0 dBm. The 1dB compression point (P1dB) is +0.5 dBm for all band.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.193-196
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• 2000

본 논문에서는 FG-CPW(Finite-Ground Coplanar Wave-Guide) 구조의 단일 평형 다이오드 믹서에 대해서 논의된다. 주파수 영역은 무선 LAN 대역으로 선택하였다. RF 신호는 5.725-5.875 GHz, LO 신호는 5.58GHz, 그리고 IF 신호는 140 MHz가 사용된다. 제시된 FG-CPW 구조의 LPF(low pass filter)는 회의크기를 줄일 수 있으며, 불필요한 하모닉 억제 특성이 우수하다. 5.635 GHz에서 5 dBm의 Power를 갖는 LO신호가 입력될 때 6.2 dB 의 혼합기의 변환손실을 얻는다. 또한 LO-RF isolation과 LO-IF isolation은 각각 30 dB $\Omega$dB 의 특성을 보인다. 이 혼합기는 CPW 구조가 일반적으로 알려진 밀리미터 대역에서의 장점뿐만 아니라 C-Band의 무선 LAN 분야에도 충분히 응용될 수 있으리라 기대된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.842-846
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• 2007

Zero Forcing (ZF) 검파 결과는 신호 대 잡음 환경이 양호한 경우 약 80% 이상이 Maximum Likelihood (ML) 검파 결과와 일치한다. 간단한 검증기를 통해 ZF 검파 결과가 ML 검파 결과와 일치하는지 알 수 있다면 검증 결과에 따라 복잡한 ML 검파 과정이나 별도의 검색 과정을 생략할 수 있다. 본 논문에서는 multiple input multiple output (MIMO) 시스템에서 ZF 검파 결과에 대한 검증 방식을 제안하였다. 제안된 검증 방식은 ZF 검파 결과를 이용하여 MIMO 신호를 single input multiple output (SIMO) 신호로 변환한 후 검파를 수행하면 안테나 다이버시티 이득을 얻을 수 있고 잡음 분산이 줄어드는 효과를 이용하였다. 제안된 검증기는 컴퓨터 시뮬레이션 결과 신호 대 잡음이 양호한 경우 80%이상의 정확한 true 판정 확률을 얻었으며 이때 false 판정 확률은 $10^{-4}$이하를 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10A
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• pp.969-979
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• 2002

This paper proposes an novel method of minimizing Interference which causes data decision error in digital wireless communications. In this method, in order to suppress ISI which is caused by the phase difference between the transmitted and received signal phases, the transmitted and received signals are always kept orthogonal by compensating the transmitted signal for detecting the phase noise and the delay of the received signal was implemented by MOS circuits. To delay the phase of the signal, additive white Gaussian noise (AWGN) environment was used. The phase and delay of the signal transmitted through AWGN channel were compensated in the modulator of the transmitter and the compensated signal was demodulated using quasi-direct conversion receiver and QPSK demodulator. ISI suppression was achieved by keeping the orthogonality between the compensated transmitted signal and the receive signal. The error probability of data decision was compared. By simulation the proposed system was proved to be effective in minimizing the ISI.