Young Yun

A novel microstrip-line structure employing a periodically perforated ground metal and its application to highly miniaturized and low-impedance passive components fabricated on GaAs MMIC

In this study, highly miniaturized and low-impedance on-chip passive components were developed using a novel microstrip-line structure employing periodically perforated ground metal (PPGM) on a GaAs monolithic microwave integrated circuit (MMIC). The proposed microstrip-line structure exhibited a much lower characteristic impedance and shorter guided wavelength than the conventional structure. Using the microstrip line with PPGM, a highly miniaturized rat-race and branch-line coupler with low-port impedances were developed for K/Ka-band MMIC applications. The miniaturized rat-race and branch-line coupler were fabricated on a GaAs substrate with a height of 100 /spl mu/m, and their sizes were 0.375 and 0.25 mm/sup 2/, respectively, which are less than 10% of the sizes of conventional ones. The miniaturized rat-race and branch-line coupler exhibited good RF performances from 20 to 30 GHz. In addition, in this study, highly miniaturized on-chip filters and biasing components were also realized using the microstrip-line structure with PPGM. The above results indicate that a microstrip-line structure with PPGM is a promising candidate for applications to highly miniaturized passive components on GaAs MMICs, and it will enable the development of fully integrated MMICs, including all passive components.

Basic RF Characteristics of the Microstrip Line Employing Periodically Perforated Ground Metal and Its Application to Highly Miniaturized On-Chip Passive Components on GaAs MMIC

In this study, highly miniaturized on-chip impedance transformers employing periodically perforated ground metal (PPGM) were developed for application to broadband low-impedance matching. In order to realize a broadband operation by using an equal ripple transfer characteristic over a passband, a three-section transformer was designed by mapping its reflection coefficient to the Chebyshev function. The three-section transformer showed a good RF performance over a broadband (1.5-13 GHz) including ultra-wideband. The size of the three-section transformer was 0.129 mm2, which is 2.3% of the size of the transformer fabricated by a conventional microstrip line. Using the PPGM structure, a highly miniaturized on-chip Wilkinson power divider with a low port impedance of 13 Omega was also developed, and its size is 0.11 mm2, which is 6% of the size of the one fabricated by the conventional microstrip line. In addition, in this study, the PPGM structure was theoretically characterized using a conventional capacitive loaded periodic structure. Using the theoretical analysis, basic characteristics of the transmission line with PPGM were also investigated in order to evaluate its suitability for application to a development of miniaturized on-chip passive components. According to the results, it was found that the PPGM structure is a promising candidate for application to a development of miniaturized on-chip components on monolithic microwave integrated circuits

A fully integrated broad-band amplifier MMIC employing a novel chip-size package

In this work, we used a novel RF chip-size package (CSP) to develop a broad-band amplifier monolithic microwave integrated circuit (MMIC), including all the matching and biasing components, for Ku- and K-band applications. By utilizing an anisotropic conductive film for the RF-CSP, the fabrication process for the packaged amplifier MMIC could be simplified and made cost effective. STO (SrTiO/sub 3/) capacitors were employed to integrate the dc biasing components on the MMIC. A novel pre-matching technique was used for the gate input and drain output of the FETs to achieve a broad-band design for the amplifier MMIC without any loss of gain. To improve the circuit stability of the amplifier MMIC in the out-of-band, a parallel RC circuit was employed at the input of the amplifier MMIC. The packaged amplifier MMIC exhibited good RF performance and stability over a wide frequency range. This work is the first report of a fully integrated CSP amplifier MMIC successfully operating in the Ku-/K-band.

A fully-integrated broadband amplifier MMIC employing a novel chip size package

In this work, using a novel RF-CSP, a broadband amplifier MMIC including all the matching and biasing components was developed for Ku and K band applications. To integrate DC biasing components on the MMIC, an STO (SrTiO/sub 3/) capacitor was employed. By employing an anisotropic conductive film for the RF-CSP, the MMIC fabrication process became very simple and cost effective. The packaged amplifier MMIC exhibited good RF performance in a wide frequency range. This work is the first report for fully-integrated Ku or K band MMICs which have all the biasing and matching components.

Experimental Study on Isolation Characteristics Between Adjacent Microstrip Lines Employing Periodically Perforated Ground Metal for Application to Highly Integrated GaAs MMICs

Using a periodically perforated ground metal (PPGM) on GaAs monolithic microwave integrated circuit (MMIC), a microstrip line structure with a high isolation characteristic between lines was developed. The high isolation characteristic was originated from a resonance between adjacent microstrip lines employing PPGM. According to experimental results, a much better isolation characteristic was observed from the adjacent microstrip lines employing PPGM compared with conventional microstrip lines, and the frequency range for high isolation was easily controlled by changing the PPGM structure. Above results indicate that microstrip lines employing PPGM are very useful for application to compact signal/bias lines of highly integrated MMIC requiring a high isolation characteristics between lines.

An ultra-compact on-chip impedance transformer fabricated using a novel microstrip line employing periodically arrayed capacitive elements on MMIC

In this work, a short wavelength microstrip line employing periodically arrayed capacitive elements (PACE) on GaAs monolithic microwave integrated circuit (MMIC) was developed for application to miniaturized on-chip passive components. The microstrip line employing PACE showed a wavelength much shorter than conventional transmission line. Concretely, the wavelength of the microstrip line employing PACE was only 10 % of conventional microstrip line on GaAs MMIC. Using the microstrip line employing PACE, a highly miniaturized impedance transformer was fabricated on GaAs MMIC. The impedance transformer showed good RF performances in a broad band from S to X band. Concretely, the return and insertion loss are −28 and −1.4 dB, respectively, at a center frequency of 7 GHz, and return loss values better than −10 dB were observed from 3.2 to 9.2 GHz, and insertion loss values of −1.5 ± 0.5 dB were observed in the above frequency range. The size of the impedance transformer was 0.042 mm2, which is 0.95 % of the size of the conventional transformer on MMIC.

Highly miniaturized passive components employing novel π-type multiple coupled microstrip lines

In this work, using a novel pi-type multiple coupled microstrip line structure (MCMLS), we fabricated highly miniaturized Wilkinson power divider and branch-line coupler. The line length of the Wilkinson power divider and branch-line coupler was reduced to about lambda/44 and lambda/38, respectively, and their size were 11.2 % and 14.6 % of conventional ones, respectively. The miniaturized Wilkinson power divider and branch-line coupler showed good RF performances in C band.

Highly miniaturized on-chip passive components fabricated by microstrip lines with periodically perforated ground metal on GaAs MMIC

In this work, using the novel microstrip line structure with PPGM (periodically perforated ground metal), highly miniaturized and low impedance on-chip passive components were realized on GaAs MMIC. The size of highly miniaturized branch-line coupler with a low port impedance of 24 /spl Omega/ was 0.25 mm/sup 2/ on GaAs MMIC, which was 10% of the one fabricated by conventional microstrip line. The branch-line coupler exhibited good RF performances from 20 to 30 GHz. In addition, in this work, highly miniaturized on-chip filter and impedance transformer were also realized using the microstrip line structure with PPGM, and they exhibited good RF performances in Ku-Ka band. The length of the open stub filter was reduced to 39% of the one fabricated by conventional microstrip line, and the size of impedance transformer was about 1% of the one fabricated by conventional microstrip line. According to the theoretical analysis, the passband of the microstrip line with PPGM was estimated to reach up to 600 GHz.

A study on RF characteristics of polyether sulfone substrate for application to flexible mobile communication device

In this work, coplanar waveguide was fabricated on flexible PES substrate, and their RF loss characteristics were extracted using transmission line theory. Concretely, several Q-factors of the coplanar waveguides were extracted using transmission line theory. Firstly, QL was characterized using the equivalent RLGC circuit. According to measured result, the QL was 25.7 at 49.8 GHz. Q-factor was also extracted from a resonant tank built using a one-quarter of a wavelength long line at the resonance frequency f0. According to the measured result, the Q-factor measured from one port open stub resonant circuit was 38.3 at a resonance frequency of 49.8 GHz, which was much higher than the open stub on silicon substrate.

A Short Wavelength and Low Loss Thin-Film Transmission Line Employing ML/CPW Composite Structure on Silicon Substrate

In this work, a thin-film transmission line (TFTL) employing microstrip line/coplanar waveguide (ML/CPW) on silicon substrate was proposed, and its RF characteristics were investigated. The TFTL employing ML/CPW composite structure exhibited the wavelength shorter than conventional coplanar waveguide and thin-film microstrip line. Concretely, at 10 GHz, the wavelength of conventional coplanar waveguide and thin film waveguide is 10.35 and 7.83 mm, while the wavelength of the TFTL employing ML/CPW composite structure was 6.26 mm, which was 60.5 % of the conventional coplanar waveguide. The TFTL employing ML/CPW composite structure with a length of λ/8 showed the loss less than 1.12 dB up to 30 GHz, which was lower than conventional coplanar waveguide and thin-film microstrip line. Above results indicates that the TFTL employing ML/CPW composite structure is a promising candidate for application to a miniaturization of RF components on silicon RFIC.