Min-Ho Go

Design and Fabrication of a Multi-Function Circuit to Implement Hybrid-Conversion RF Front-End for Broadband and Multiband System

In this paper, we propose a RF front-end architecture based on hybrid conversion which is available to receive both broadband and multiband DVB-H receiver, and a multi-function circuit for implementing the RF front-end is fabricated. A multi-function circuit is operated as a sub-harmonic mixer mode in the case of receiving a broadband VHF/UHF band, which show a conversion loss of -10.0 dB, noise figure of 7.0 dB and IIP3 of 2.0 dBm. On the other hand, it is performed as a attenuation mode with a insertion loss of -10.0 dB in receiving a multiband, L-band.

Design and Implementation of Broadband RF Amplifier for Microwave Receiver

In this paper, We proposed a broadband RF amplifier for Microwave band receiver. We also proposed a broadband RF amplifier, designed by using EM simulation for reliable amplification of the received signal. Connected to a source terminal to via, it minimizes those which are the active elements of source-side oscillation as the operating element in an ideal GND, and a constant gain characteristic in a broadband. The goal of this was to obtain stable amplification characteristics. For implementing this architecture, we designed the broadband(500 MHz ~ 7 GHz) RF amplifier by using commercial GaAs FET, which operate on 720 MHz, 4,595 MHz, and 6,035 MHz by impedance matching. The voltage gain is 10.635 dB ~ 14.407 dB(737.5 MHz ~ 6.0575 GHz), P1dB is 20 dBc of band(1st harmonic/2nd harmonic).

Design and Implementation of Ku-Band VCO for Microwave Multi-Band Receiver

In this paper, we propose the architecture of a multi-band receiver which can receive X-band, Ku-band, K-band and Ka-band signals. For implementing this architecture, we designed a wideband and high power VCO with a buffer stage. In order that a buffer does not affect the characteristic of a oscillation in steady state condition, output impedance of a oscillation part and input impedance of a buffer are orthogonally crossed. The fabricated VCO meets the performance parameter of the multi-band receiver which has a bandwidth with respect to the tuning voltage, , and output power of .

Simplified multiband front-end architecture using a multifunction circuit

A multifunction circuit to simplify a multiband front-end operating at very different bands is proposed. The multifunction circuit operates as a sub-harmonic mixer or an attenuator depending on a control voltage. A multiband front-end using the proposed multifunction circuit can reduce component, is 23 percent smaller, and is less expensive compared to a conventional architecture with a switching circuit.

Design and Implementation of Multi-Function Conversion Block for Microwave Receiver

본 논문은 마이크로웨이브 수신기 구성을 위한 다기능 주파수 변환 블록을 설계 및 제작하였다. 제안한 다기능 주파수 변환 블록은 광대역 전압제어발진기와 이중모드 주파수 혼합기로 구성되어, 바이어스 전압 인가 여부에 따라 마이크로 웨이브 수신기에 필요한 첫 번째 IF(Intermediate Frequency) 출력 주파수 4,595 MHz / 6,045 MHz는 720 MHz로 주파수 변 환을 하고, Ku-대역 수신을 위한 IF 출력 주파수 720 MHz는 주파수 변환을 하지 않고 통과(bypass) 및 감쇄시키는 이중모 드의 다기능 동작을 한다. 제작 및 측정결과, 각 중간주파수에서 LO 전력에 따른 변환손실 특성은 2~4 dBm의 LO 레벨 에서 4,595 MHz는 13 dB, 6,035 MHz에서 12 dB, 720 MHz에서는 7.0 dB의 변환손실 특성을 나타내었다.

Varactor-Diodeless VCO for Radar Signal Detection Applications

In this paper, we propose a varactor-diodeless voltage-controlled oscillator operating at X-band, and verify the possibility of applying to a receiver for microwave radar signal detection applications. The proposed VCO is realized by only single RF BJT device as a varactor diode is substitued by a intrinsic collector-base PN-junction of the active device which is used to generate negative resistance. The fabricated VCO meets the specification of the receiver, which has a 11.20~11.75 GHz tuning bandwidth with respect to the tuning voltage, 1.0~7.0 V, output power of 9.0~12.0 dBm and linear frequency tuning performance.

Realization of Power Amplifier Using a Harmonic Rejection Circuit

In this paper, I study on the realization of 900 MHz 1 W power amplifier using a harmonic rejection circuit. The proposed harmonic rejection circuit has improved the harmonic rejection characteristic and overcoming the problems related with frequency reproducibility on the microstrip line. The proposed power amplifier, fabricated by the type of hybrid with the epoxy PCB, was composed of driver stage and power amplifier stage with harmonic rejection circuit. The fabricated power amplifier shows -24 dBc and -30 dBc of harmonic rejection characteristic at 2nd and 3rd harmonic compared with that is not used, respectively and it could be replace the filter located between an output stage and an antenna.