Jeong-Seok Jang

W-CDMA High Power Amplifier using Anti-Phase Intermodulation Distortion Linearization Technology

This paper shows how the ACLR of power amplifier can be reduced by using Anti-phase IMD linearization technique which generate Anti-phase IMD in the driver stage compare to output stages IMD. Brief theory and design process are proposed. From the experimental result of 4-carriers W-CDMA input signal, this amplifier has ACLR -55 dBc@5 MHz offset at 44.7 dBm(30 watts) average output power. Compare to optimum matching technique to get maximum power gain, this technique has been improved ACLR by 12 dBc.

The calculation of field strength for DTV receiver by Rec. ITU-R P.1546

We propose the methodology of field strength prediction for a digital television (DTV) receiver by virtue of Rec. ITU-R P.1546. The curves shown in this Rec. represent the point-to area field strength for 1kW effective radiated power in the 30 MHz ∼ 3000 MHz. Some computed results are illustrated here from the formulation of field strength for DTV receiver. It was shown that the error of field strength value for dense urban area (R = 30 m) is in the range of about 6.8 ∼ 11.5 % compared with the Okumura-Hata model under some conditions. In addition comparison of service distance between analog and digital TV receivers has been also illustrated. The presented method provides the predicted values of field strength for TV receiver whether transmission quality can be assured or not, and it can be also used to get the protection ratio or separated distance for frequency sharing in the same or adjacent band.

A Study on the Prediction of Electric Field Strength for Terrestrial TV Broadcasting by Digital Adoption

In this paper, we propose a calculation methodology of the service distance to assure the satisfactory quality of service for analogue and digital TV receivers. Using the field strength formulation for TV receiver based upon Rec. ITU-R P.1546, computational results are presented and discussed for both systems, and some important factors are reviewed in terms of the equivalent level of service, which must be kept due to ATV to DTV conversion. The presented method provides the predicted values of field strength at receiver areas to check whether transmission quality can be satisfied or not, and it can be also used for obtaining the protection ratio or separated distance from co-channel or adjacent interference signal.

A Design of New Digital Adaptive Predistortion Linearizer Algorithm Based on DFP(Davidon-Fletcher-Powell) Method

In this paper, a new linearization algorithm for DPD(Digital PreDistorter) is suggested. This new algorithm uses DFP(Davidon-Fletcher-Powell) method. This algorithm is more accurate than that of the existing algorithms, and this method renew the best-fit value in every routine with out setting the initial value of step-size. In modeling power amplifier, the memory polynomial model which can model the memory effect of the power amplifier is used. And the overall structure of linearizer is based on an indirect learning architecture. In order to verify for performance of proposed algorithm, we compared with LMS(Least Mean-Squares), RLS(Recursive Least squares) algorithm.

The improvement of VCO performance based upon in/out common frequency tuning

In this paper, we presented a K-band Voltage Controlled Harmonic Oscillator(VCHO) with novel structure. The proposed VCHO is a structure of two hair-pin resonators placed on input and output of active device. By using in/out common frequency tuning structure, the VCHO produced some advantages of the enhanced characteristics of fundamental frequency suppression as well as the improved second harmonic output power. According to measurement results, it has been shown that a VCHO provide the output power of −2.41 dBm, fundamental frequency suppression of −21.84 dBc, and phase noise of −101.44 dBc/Hz@100 kHz. In addition, output frequency range of 10.58 MHz could be obtained with a power variation of +/−0.19 dB over its frequency range with respect to the bias voltage from 0 to −10 V for the varactor diode.

A Study on the Improvement of Performance in VCO Using In/Out Common Frequency Tuning

In this paper, a VCHO(Voltage Controlled Harmonic Oscillator) for K-band application has been designed and implemented. The proposed oscillator has a structure of two hair-pin resonators placed on input and output of active device. Using in/out common frequency tuning structure, the VCHO yields some advantages of the enhanced fundamental frequency suppression characteristic as well as the improved output power of second harmonic. According to implementation and measurement results, it was shown that a VCHO provides an output power of -2.41 dBm, a fundamental frequency suppression of -21.84 dBc, and phase noise of -101.44 dBc/Hz at 100 kHz offset. In addition, as for the bias voltage from 0 V to -10 V for the varactor diode, output frequency range of 10.58 MHz is obtained with a power variation of over its frequency range.