Jeong-Gab Ju

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.

Direct Conversion Mixer IC for Application to Long Distance Wireless Power Transmission

In this paper, Using the silicon CMOS technology, direct conversion mixer was fabricated on silicon substrate for a realization of the long distance wireless power transmission system. The size of the mixer is 0.8 mm × 0.5 mm. The input frequency of mixer is 24 GHz, and converted BB frequency is 30 MHz. The conversion loss and output power of mixer was -9 dB and -10 dBm, respectively.

Tranceiver Mixer MMICs Employing Cascode Circuit Structure for Personal Area Network (PAN) Applications

MMIC (monolithic microwave integrated circuit) chip set was developed for application to wireless PAN. Concretely, cascade type transceiver mixers employing GaAs p-HEMT were fabricated on GaAs substrate. The mixer MMICs showed good RF performances. Concretely, the conversion gain of the receiver mixer was 9.6 dB at a LO input of 8 dBm, and 9.6 ± 1.6 dB at a RF frequency range of 62.5 - 63.5 GHz. The chip size of the receiver mixer was 2.7 mm x 1.35 mm. The conversion gain of the transmitter mixer was 6.5 dB at a LO input of 8.5 dBm, and 6.5 ± 0.25 dB at a IF frequency range of 1.9 - 2.9 GHz. The chip size of the transmitter mixer was 2.7 mm x 1.35 mm. 0.2 μm

A Fully-Integrated High Stable Broadband Amplifier MMICs Employing Simple Pre-matching/Stabilizing Circuits

In this work, using simple low-loss pre-matching/stabilizing circuits, high stable broadband driver amplifier (DA) and medium power amplifier (MPA) MMICs including all the matching and biasing components were developed for K/Ka band applications. The DA and MPA MMICs exhibited good RF performances and stability in a wide frequency range. The layout size of the DA and MPA MMICs were 1.7X0.8 and 2.0X1.0 μm2, respectively.

A Fully-Integrated Amplifier MMIC Employing a CAD-Oriented MIM Shunt Capacitor

In this work, using a CAD-oriented MIM shunt capacitor appropriate for circuit/layout design in millimeter-wave applications, a highly integrated broadband amplifier MMIC including all the matching components was developed for K band applications. Concretely, bulky power divider and combiner were highly miniaturized using the CAD-oriented MIM shunt capacitor, and they were all integrated on MMIC. In addition, the CAD-oriented MIM shunt capacitors were employed for capacitive matching in place of bulky open stubs. The amplifier MMIC exhibited good RF performances and good stability in a wide frequency range from 17 to 28 GHz. The layout size of the amplifier including all passive components was 2.0X1.0 mm2.

Equivalent Circuit Model of Comb-type Capacitive Transmission Line on MMIC for Application to the RF Component Design in Millimeter-Wave Wireless Communication System

In this work, the equivalent circuit of comb-type capacitive transmission line (CCTL) structure was investigated using theoretical analysis. The equivalent circuits for CCTL cell were extracted, and all lumped circuit parameters were expressed by closed-form equation. A fairly good agreement between calculated and measured results were observed up to 50 GHz. Above results indicate that the proposed equivalent circuit model can be efficiently used for application to millimeter-wave wireless communication system.

A Study on Equivalent Circuit of Short Wavelength Coplanar Waveguide Employing Periodic Ground Structure on Silicon RFIC

In this paper, equivalent circuit of short wave length coplanar waveguide employing Periodic Ground Structure on Silicon (PGSS) were investigated using theoretical analysis. Equivalent circuits for the PGSS cell were extracted, and all lumped circuit parameters were expressed by closed form equation. A fairly good agreement between calculated and measured results were observed from 0 to 25 GHz. Above results indicate that the proposed equivalent circuit can be efficiently used up to K band.

Basic Study on the Radio Frequency Characteristics of the Transmission Lines Employing Periodically Perforated Ground Metal on GaAs Monolithic Microwave Integrated Circuit and Their Equivalent Ciruits

In this work, basic characteristics of transmission line employing periodically perforated ground metal (PPGM) were investigated using theoretical and experimental analysis. Concretely, bandwidth and impedance were investigated using theoretical analysis, and wavelength and effective permittivity were extracted from experimental results. In addition, insertion loss and isolation characteristics were investigated using equivalent circuit analysis. For simplification of design process, equivalent circuits for the PPGM cell were extracted, and all circuit parameters were expressed by closed-form equation. Above results indicate that the transmission line employing PPGM is a promising candidate for a development of matching and passive elements on monolithic microwave integrated circuit (MMIC) including wireless communication circuit and compound semiconducting devices such as high electron mobility transistor (HEMT), diamond field effect transistor (FET) and light emitting diode (LED).

Ultra-compact RF passive components employing periodically arrayed ground structure on silicon RFIC

In this work, using a coplanar waveguide employing periodically arrayed ground structure (PAGS) on silicon RFIC, a highly miniaturized and broadband on-chip impedance transformer and 90° hybrid coupler were developed for application to wireless communication system. The size of the impedance transformer was 0.01mm2 on silicon substrate, which was 6.99% of the one fabricated by conventional coplanar waveguide. The transformer showed a good RF performance from 1 to 40 GHz. The 90° hybrid coupler exhibited good performances from 41.75 to 50 GHz, and its size was 0.46×0.55 mm2, which is 37% of conventional one.

Highly miniaturized LO leakage rejection filters employing spiral lines for application to Ku-band commercial wireless communication system

In this work, spiral inductor structures employing SiN film were fabricated on GaAs substrate for a suppression of LO and its second harmonic leakage signals. Concretely, they were properly designed so that the self-resonance frequency was accurately tuned to LO and its second harmonic frequency, and they were integrated on the downconverter MMIC. Owing to the optimally designed on-chip spiral inductor filters, the downconverter MMIC showed a highly suppressed LO leakage power of −35 dBm and second harmonic LO leakage power of −53 dBm without external filters.