Sang Soo Park

Design of new three-line balun and its implementation using multilayer configuration

This paper proposes a new balun that is composed of three coupled quarter-wavelength lines. The proposed balun is optimized by using design of experiments to achieve a maximum bandwidth. After the optimization, it is transformed into the balun consisting of a pair of coupled quarter-wavelength lines in connection with an uncoupled quarter-wavelength line. The design method and its implemented results using a multilayer configuration are presented. It is shown that this new balun can be made more compact, providing good performances over the wide frequency range. Therefore, the balun developed here is applicable to many wireless and mobile communication systems. The design equation for a given set of balun impedances at unbalanced and balanced ports is derived from an equivalent circuit of the proposed balun. To demonstrate the feasibility and validity of the design equation, the size 2012 multilayer ceramic chip baluns with three different balun impedances, which operated in the 2.4-GHz industrial-scientific-medical band frequency, are designed and fabricated by the use of low-temperature co-fired ceramic technology. According to the measured results, the maximum insertion loss is 0.81 dB, the maximum in-band phase imbalance is within 7/spl deg/, and the maximum in-band amplitude imbalance is less than 0.7 dB.

Feed-Through Type Multilayer Capacitor for High Frequency Voltage Noise Suppression

A novel feed-through type multilayer ceramic capacitor (MLCC) is proposed using vertically oriented internal electrodes. The proposed capacitor has a distinctive structure to effectively reduce the parasitic equivalent series inductance (ESL), and thus the noise suppression performance of the capacitor can be greatly improved. Furthermore, it can be made compact with the help of relatively simple terminal structure. Therefore, the capacitor developed here is suitably used as a bypass capacitor in mobile communication systems where miniaturized components with high performance are essentially required. To demonstrate the feasibility and validity of the proposed capacitor, the size 1005 capacitors and evaluation boards have been designed and fabricated. According to the measured results, the proposed capacitor provides the insertion loss of 47.5 dB at 1.0 GHz, and thus the peak to peak voltage noise is reduced from 352 mV to 287 mV by using the proposed capacitor instead of using the regular two terminal MLCC.

Improvement of out-of-passband characteristics for a laminated chip bandpass filter using tapped resonator

This paper presents how a tapped resonator can be used to improve out-of-passband characteristics and as an example, a laminated chip bandpass filter using tapped resonators is designed and fabricated with silver paste and high permittivity multilayer ceramic in the MgTiO/sub 3/ and CaTiO/sub 3/ system. Its size is 2.5 mm/spl times/2.0 mm/spl times/0.95 mm. The measured frequency characteristics of the fabricated filter are presented and compared with the simulated ones. Using the tapped resonator, the filter exhibits excellent out-of-passband performances suitable for wireless LAN and Bluetooth applications.