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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.

In this paper, a study is presented of the dynamic behavior of an automatic transmit power control (ATPC) loop in a single fixed wireless system (FWS) link subject to multipath fading and an uncorrelated co-channel interferer that does not use ATPC (this represents a so-called non-ATPC FWS link or a fixed satellite link). Fundamental questions include the sensitivity of an ATPC link to multipath interference and the co-channel interference that may be caused by a non-ATPC interferer. In the context of the present project, a good example of a non-ATPC interferer is a fixed satellite to which one antenna in a fixed microwave link has partial view. A computer model was developed that constitutes a useful tool in describing; simulating and analyzing an ATPC loop in a single FWS link. With the aid of this model, results are presented on the sensitivity of an ATPC loop in a FWS link with respect to channel conditions, non-ATPC interference and parameter settings.

This paper suggests an efficient and comprehensive algorithm of protection ratio derivation and illustrates some calculated results applicable to the initial planning for frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current M/W frequency band of 6.7 GHz including Tx spectrum mask and Rx filter response. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also capable of applying the same concept to frequency coordination of the fixed millimeter wave networks.

As an oxidation resistant layer, silicon nitride film has been widely used in semiconductor processes. Normally, silicon nitride deposition induces strong tensile stress on the silicon wafer. This stress also contributes to the wafer warpage. In order to investigate the relationship between this phenomenon and electrical properties of device, we prepared silicon nitride coated wafers with different film thickness. After the silicon nitride deposition on both sides of wafers, we stripped full of the film or half of the film on the backside surface. For each and every wafer, the degree of warpage and the electrical characteristics were measured. In this paper, we reported the warpage trend according to the silicon nitride film thickness and to the area of nitride stripped backside surface. Besides, we observed breakdown voltage difference depending on the degree of warpage.

The growing demand for high capacity transmission in digital radio systems (DRS) has led to the adoption of a highly spectral efficient system comprising cochannel operation and multilevel QAM. Due to the vulnerability of such a system to the channel conditions, great efforts have been made on counteracting multipath fading and depolarization. The authors propose a powerful multitask chip with 150 K gate array for DRS. This chip was implemented with state of the art 0.6 /spl mu/ HCMOS technology and was designed to be used not only as an equalizer for multipath fading and a canceller for cochannel operation, but also as a digital filter for pulse shaping in modems using up to 1024-QAM or TCM. The performance of cochannel of 64-QAM DRS combined with digital slope equalizer is presented. >

In the microwave imaging of conducting scatterer, a spatial slice theorem may be introduced and a computerized tomographic (CT) algorithm may directly be employed in reconstructing images without interpolation processing. It is noted that the same concept may also be applied to the reconstruction of dielectric objects in the sense of the Born approximation. It is shown that the discrete Fourier transform of the normalized backscattered field yields the projection function which makes possible the reconstruction of the distribution of dielectric constants through the CT algorithm. Furthermore, the limiting factors in the degraded reconstructed image due to the Born approximation are identified in terms of the projection function, and its modification is suggested for improving the algorithm based upon the Born approximation. >

The limited frequency resources and the growing demand for high capacity transmission in digital radio systems (DRS) have led to the adoption of multi-level QAM and cochannel operation with cross polarization interference canceler (XPIC). This article describes a powerful multi-task ASIC chip with 165 K gate array for DRS applications. This was implemented on one chip by a state of the art 0.6 /spl mu/m HCMOS technology and designed not only for a complex equalizer and a canceler of up to 256QAM for multipath fading and cochannel operation, but also for a digital filter (DF) for pulse shaping up to 1024QAM or TCM. The superior performance for cochannel DRS with 64QAM is presented by numerical analysis and experimental results.