• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1169-1176
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• 2010

The RF front-end for L1/L2 dual-band Global Positioning System(GPS) receiver is presented in this paper. The RF front-end(down-converter) using low IF architecture consists of a wideband low noise amplifier(LNA), a current mode logic(CML) frequency divider and a I/Q down-conversion mixer with a poly-phase filter for image rejection. The current bleeding technique is used in the LNA and mixer to obtain the high gain and solve the head-room problem. The common drain feedback is adopted for low noise amplifier to achieve the wideband input matching without inductors. The fabricated RF front-end using $0.18{\mu}m$ CMOS process shows a gain of 38 dB for L1 and 41 dB for L2 band. The measured IIP3 is -29 dBm in L1 band and -33 dBm in L2 band, The input return loss is less than -10 dB from 50 MHz to 3 GHz. The measured noise figure(NF) is 3.81 dB for L1 band and 3.71 dB for L2 band. The image rejection ratio is 36.5 dB. The chip size of RF front end is $1.2{\times}1.35mm^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.7
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• pp.675-678
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• 2015

In this paper, we proposed a multi-function conversion block for microwave receiver. The proposed multi-function conversion block is composed of a broadband voltage controlled oscillator and a dual-mode mixer. Depending on whether the bias voltage is supplied, the first IF(Intermediate Frequency) output frequency(4,595 MHz/6,045 MHz) needed in microwave receiver is converted to 720 MHz and the another IF output frequency(720 MHz) for receiving Ku-band has the multi-functional operations of the dual mode that are bypass and attenuation without frequency conversion. Implementation and measurement results show that each intermediate frequency has conversion loss characteristic according to the LO power. The LO power conversion loss of 4,595 MHz at the LO levels from 2 dBm to 4 dBm is 13 dB, another of 6,035 MHz is 12 dB and the other of 720 MHz is 7.0 dB.

• Journal of The Korean Astronomical Society
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• v.46 no.6
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• pp.225-234
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• 2013

We develop a radio receiver system operating at ${\lambda}{\sim}1.3$ mm for the 6 m telescope of Seoul Radio Astronomy Observatory. It consists of a dual polarization receiver, a couple of IF processing units, two FFT spectrometers, and associated software. By adopting sideband-separating superconductor mixers with image band terminated to waveguide load at 4.2 K, we achieve $T_{RX}{\leq}100$ K and $T_{sys}$ less than 150 K at best weather condition over 210-250 GHz frequency range. The intermediate frequency signal of 3.5-4.5 GHz is down converted to 0-1 GHz and fed into the FFT spectrometers. The spectrometer covers 1 GHz bandwidth with a spectral resolution of 61 KHz. Test observations are conducted toward several radio sources to evaluate the performance of the system. Aperture and beam efficiencies measured by observing planets are found to be typically 44 ~ 59% and 47 ~ 61%, respectively over the RF band, which are consistent with those measured at 3 mm band previously.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.1
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• pp.24-29
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• 2009

In this paper, we show the implementation of the low-cost RF transceiver module for parking control system. Super regenerative receiver scheme was adopted for this module due to its simplicity, low-cost, low power consumption and small number of components to improve reliability of the systems. For improving communication error rate by collision and in-band noise, dual-channel hopping scheme was adopted. Testing prototypes under the environment of simultaneous transmissions, we verified that the designed scheme is able to improve the success rate of data transmission of wireless parking control system cost effectively.

• ETRI Journal
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• v.9 no.3
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• pp.74-85
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• 1987

In this paper, a new kind of dual tone multifrequency receiver(DTMFR) is proposed, in which detection is made in terms of the partial correlation(PARCOR) coefficients for efficient DTMF signal detection against both temporary decoding errors by crosstalks possibly coming from adjoint telephone lines during transmission and so-called digit simulation by background voice or noise signals during interdigit period. A simulation study on the behaviour of PARCOR coefficients for tone signals and non-signals has been performed in order to provide the rationale on the feasibility of the proposed DTMFR algorithm. Based upon simulation results, a more refined detection strategy as an example is presented and explained together with the corresponding decision logic.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.2
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• pp.71-81
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• 2014

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.345-353
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• 2013

A W-band Orthomode Transducer (OMT) has been developed for Korean VLBI Network (KVN) polarization observation. The OMT design was based on E-plane split-block technique using septum structure. 3-dimensional electromagnetic simulation was fully employed to optimize the performance of the OMT. Measurements of the fabricated OMT show that the return losses for the vertically and horizontally polarized modes are better than -20 dB across 80 ~ 108 GHz and the insertion losses for the both modes are less than 0.47 dB. The cross-polarization level of the OMT is less than -30 dB. The bandwidth of the developed OMT is estimated as around 30%.

• ETRI Journal
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• v.30 no.2
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• pp.268-274
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• 2008

This paper proposes an open-loop clock recovery circuit (CRC) using two high-Q dielectric resonator (DR) filters for 39.8 Gb/s and 42.8 Gb/s dual-mode operation. The DR filters are fabricated to obtain high Q-values of approximately 950 at the 40 GHz band and to suppress spurious resonant modes up to 45 GHz. The CRC is implemented in a compact module by integrating the DR filters with other circuits in the CRC. The peak-to-peak and RMS jitter values of the clock signals recovered from 39.8 Gb/s and 42.8 Gb/s pseudo-random binary sequence (PRBS) data with a word length of $2^{31}-1$ are less than 2.0 ps and 0.3 ps, respectively. The peak-to-peak amplitudes of the recovered clocks are quite stable and within the range of 2.5 V to 2.7 V, even when the input data signals vary from 150 mV to 500 mV. Error-free operation of the 40 Gb/s-class optical receiver with the dual-mode CRC is confirmed at both 39.8 Gb/s and 42.8 Gb/s data rates.

• Publications of The Korean Astronomical Society
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• v.18 no.1
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• pp.51-60
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• 2003

This paper is the research and development including the system design and the prototype system building of the 400MHz wide-band digital autocorrelation spectrometer system for radio astronomy observation, which will be used as back-end signal processing unit of the Dual channel SIS receiver at Taeduk Radio Astronomy Observatory. So in this paper, we performed development of the high speed digitizing sampler, the circular memory buffer, and the correlator module for the 400MHz wide-band digital autocorrelator. This developed system will be use at TRAO after the housing and some calibration.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.233-237
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• 2017

The dual-channel receiver MMIC which is composed of LNA, Mixer, LO-amp and temperature compensation circuit is designed on a single chip. For the performance comparison, a FMCW radar transceiver module using commercial MMICs is also implemented. As a result, Multi-channel Transceiver using manufactured MMIC shows an improved performance such as noise figure and gain flatness compare to purchased MMIC.