• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.9-14
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• 2002

Direct-conversion receiver(DCR) architecture has superior advantages in size, cost, and power over superheterodyne receiver architectures. However, the use of direct-conversion receiver architecture has been limited due to the direct-current offset noise. The ac coupling, which is used to overcome the direct-current offset noise, causes an inter-symbol interference(ISI), whose effects can be effectively mitigated using an equalizer. In this paper, the performance of a direct-conversion receiver with ac coupling in the presence of direct-current offset is analyzed via computer simulation. The simulation result shows that by using decision feedback equalizer with LMS(Least Mean Square) algorithm, signal-to-noise ratio loss of the direct-conversion receiver compared to the idea receiver can be reduced to less than 1㏈ for corner frequencies as large as 10% of the symbol rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.129-135
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• 2010

In this paper, we propose and demonstrate a new four-port BPSK direct conversion receiver based on $0.18\;{\mu}m$ CMOS technology for K-band applications. The proposed direct conversion receiver is composed of two active combiners, an lumped LC balun, two power detectors and an analog decode. The designed direct conversion receiver is successfully demodulated BPSK signal with 40 Mbps in the K-band.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.361-364
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• 2000

One of the problems using DCR(Direct Conversion Receiver) are DC offset, poor channel selectivity. APDP(Anti Parallel Diode Pair) can be good candidate for DCR frequency mixer due to its inherent End harmonic suppression. APDP shows good IP2 and DC suppression. This paper describe single APDP LO power characteristics, IP2, and receiver structure utilizing APDP frequency mixer

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.668-675
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• 2001

Recently, the performance of the commercial PCS(Personal Communication Service) system has been improved to the uppermost limit and ultimately the next generation mobile communication is to be realized by IMT-2000 (International Mobile Communication-2000) to provide multimedia services. Therefore, the new type receiving system is researched actively and one of the most important part in a receiver is direct conversion method. The direct conversion method is suitable for low power consumption, small size, MMIC, and low price, which is to be adopted to the next generation mobile communication systems. In this case, however, several problems occur due to DC-offset. The DC-offset suppresses amplification of the required signal because of the leakage signal of frequency synthesizer in the system. In this thesis, the removing method of DC-offset was considered. There are four removing techniques of DC-offset, which are AC-coupling, large capacitor, DC-feedback loop, and DC-free coding. Among these, the AC-coupling method is the most simplest method and the DC-feedback loop method has the best performance. Then, the performance of the AC-coupling method and DC-feedback loop method are evaluated by HP's ADS simulation tool. As a result, the AC-coupling method cannot be used to the digital communication systems due to data loss. On the other hand, it was confirmed that the DC-feedback loop method is suitable for the direct conversion receiver.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.64-71
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• 2008

SAW (Surface Acoustic Waves) ID (identification) tags have been designed and implemented for RFID (Radio frequency IDentification) systems. With SAW ID tag of pulse position encoding method, the data capacity increased 3 times compared with SAW ID tag of amplitude on/off method. Two different kinds of SAW ID tag receiver systems, heterodyne and homodyne receiver systems, were made. The direct conversion receiver showed better isolation property, 10 dB improvement than the heterodyne receiver to increase wireless interrogation distance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1464-1469
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• 2008

A CMOS Gm-C filter with variable cutoff frequency applicable for using in the direct conversion receiver is designed. The designed filter comprises the CMOS differential transconductors, and the gm of the transconductor is controlled by the bias voltage. This configuration can compensate variant of the cutoff frequency which could be generated by external noises, and also be used in multiband receiver. As a results of HSPICE simulation, the control range of the cutoff frequency is $1.5MHz{\sim}3.5MHz$ and the gain control range is $-2.8dB{\sim}2.6dB$. The layout of the designed 5th-order Elliptic low-pass filter is performed to fabricate a chip using $2.5V-0.25{\mu}m$ CMOS processing parameter.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.154-157
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• 2000

One of the problems using DCR(Direct Conversion Receiver) type architecture are DC offset, Poor channel selectivity. APDP(Anti Parallel Diode Pair) can be mood candidate for the DCR frequency mixer due to its inherent 2nd harmonic suppression. APDP shows good IP2 and DC suppression. This paper describes single APDP LO power characteristics, IP2, and receiver structure utilizing APDP frequency mixer.

• The Magazine of the IEIE
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• v.29 no.9
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• pp.48-67
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• 2002

Basic introduction to direct conversion architecture was given in comparison with heterodyne one. Principal difficulties in implementation of direct conversion receiver were presented, current state of research in this field and classified, on the basis of extensive analysis of published materials.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1534-1540
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• 2005

The direct conversion method is classified into the structure using the mixing technology and six-port scheme. In the view point of complexity and integration the direct conversion method using the six-port scheme is superior to that with mixing technology. Expecially, the six-port direct conversion technology provides the low power consumption and the broad-band characteristic. In this paper, the six-port direct conversion receiver with the branch-line coupler and the ring hybrid coupler is desisted respectively. The performances of the designed six-port schemes are analyzed and the six-port scheme with superior performance characteristics is proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.481-484
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• 2005

The direct conversion method is classified into the structure using the mixing technology and six-port scheme. In the view point of complexity and integration the direct conversion method using the six-port scheme is superior to that with mixing technology. Expecially, the six-port direct conversion technology provides the low power consumption and the broad-band characteristic. In this paper, the six-port direct conversion receiver with the branch-line coupler and the ring hybrid coupler is designed respectively. The performances of the designed six-port schemes are analyzed and the six-port scheme with superior performance characteristics is proposed.