• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.125-131
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• 2002

This paper presents MMIC drive and power amplifiers covering 6-18 ㎓. For simple wideband impedance matching and less sensitivity to fabrication variation, modified distributed topologies are employed in the both amplifiers. Cascade amplifiers with a self-biasing circuit through feedback resistors are used as unit gain blocks in the drive amplifier, resulting in high gain, high stability, and compact chip size. Self impedance matching and high-pass, low-pass impedance matching networks are used in the power amplifier. In measured results, the drive amplifier showed good return losses ($S_11,{\;}S_{22}{\;}<{\;}-10.5{\;}dB$), gain flatness ($S_{21}={\;}16{\;}{\pm}0.6{\;}dB$), and $P_{1dB}{\;}>{\;}22{\;}dBm$ over 6-18 GHz. The power amplifier showed $P_{1dB}{\;}>{\;}28.8{\;}dBm$ and $P_{sat}{\;}{\approx}{\;}30.0{\;}dBm$ with good small signal characteristics ($S_{11}<-10{\;}dB,{\;}S_{22}{\;}<{\;}-6{\;}dB,{\;}and{\;}S_{21}={\;}18.5{\;}{\pm}{\;}1.25{\;}dB$) over 6-18 GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.720-725
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• 2015

This paper describes the design of a wideband cascode amplifier using a feedback network and microwave small-signal transistors. The adopted cascode structure enables the miller effect to be lessened, cutoff frequency to increase, and reduction of gain in the mid-band to be mitigated. In addition, a feedback network is added to the cascode structure to improve the input matching and ripple performances over the wide operating band. The designed cascode amplifier contains a feedback network for small size and broadband amplification, whereas balanced amplifiers and distributed amplifiers have been used widely. The measurement shows $8.5dB{\pm}1.5dB$ of gain over 1000-2000MHz. The fabricated cascode amplifier has more than 8dB of gain over a 1000MHz bandwidth with a good flatness. The measured performances agree with the predicted ones even a minor shift in operating frequency is observed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.483-489
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• 2006

In this paper, new wideband lens amplifiers are proposed for C-band wireless communication service. In order to obtain the wideband property, all components of the proposed lens amplifiers are designed with balanced structure and wideband characteristics. Fat dipole antenna as the input and output antenna, balanced amplifier as amplifying components, and coplanar stripline(CPS) as the delay line fer the beam focusing are used fur composing the stable wideband lens amplifier. The $5{\times}5$ 2D lens amplifier has the characteristics that the absolute gain is 7.5 dB, the EIPG is 37.4 dB at 6 GHz, and the 3-dB gain bandwidth is 19.8 %.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1817-1823
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• 2009

A design of cascaded distributed amplifier with a broadband amplification is described in this paper. A medium power device with 23dBm, max output power under the optimal narrow-band power matching condition is adopted for the design and fabrication of the cascaded distributed amplifier. In general, conventional distributed amplifiers with the parallel connected input ports have a low gain, and previous cascaded distributed amplifiers show a relatively low output power of 10dBm at most, which is the upper limit of small signal amplification. However, the cascaded distributed amplifier in this paper shows the gain of $18.15{\pm}0.75dB$ and output power of 20dBm over $300MHz{\sim}2GHz$ from the measurement, so it can be well adopted as a wideband driver amplifier.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.44-51
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• 2016

A commercial $0.25{\mu}m$ GaN process is used to implement 6-18 GHz wideband power amplifier (PA) monolithic microwave integrated circuits (MMICs). GaN HEMTs are advantageous for enhancing RF power due to high breakdown voltages. However, the large-signal models provided by the foundry service cannot guarantee model accuracy up to frequencies close to their maximum oscillation frequency ($F_{max}$). Generally, the optimum output load point of a PA varies severely according to frequency, which creates difficulties in generating watt-level output power through the octave bandwidth. This study overcomes these issues by the development of in-house large-signal models that include a thermal model and by applying distributed L-C output load matching to reactive matched amplifiers. The proposed GaN PAs have successfully accomplished output power over 5 W through the octave bandwidth.

• ETRI Journal
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• v.42 no.5
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• pp.773-780
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• 2020

A 40 nm complementary metal oxide semiconductor carrier-aggregated drive amplifier with high linearity is presented for sub-GHz Internet of Things applications. The proposed drive amplifier consists of two high linear amplifiers, which are composed of five differential cascode cells. Carrier aggregation can be achieved by switching on both the driver amplifiers simultaneously and combining the two independent signals in the current mode. The common gate bias of the cascode cells is selected to maximize the output 1 dB compression point (P1dB) to support high-linear wideband applications, and is used for the local supply voltage of digital circuitry for gain control. The proposed circuit achieved an output P1dB of 10.7 dBm with over 22.8 dBm of output 3rd-order intercept point up to 0.9 GHz and demonstrated a 55 dBc adjacent channel leakage ratio (ACLR) for the 802.11af with -5 dBm channel power. To the best of our knowledge, this is the first demonstration of the wideband carrier-aggregated drive amplifier that achieves the highest ACLR performance.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.167-170
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• 2002

The design and fabrication of Q-band 3-stage monolithic microwave integrated circuit(MMIC) driver and power amplifiers for WLAN are presented using 0.2${\mu}{\textrm}{m}$ AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor(PHEMT). In each stage of the MMIC DA, a negative feedback is used for both broadband and good stability. The MMIC PA has employed a balanced configuration to overcome these difficulties and achieve high power with low VSWR over a wide frequency range. In the MMIC DA, the measurement results arc achieved as an input return loss under -4dB, an output return loss under -l0dB, a gain of 14dB, and a PldB of 17dB at C-band(36~ 44GHz). The chip size is 28mm$\times$1.3mm. The developed MMIC PA has the l0dB linear gain over 360Hz to 420Hz band and 22dBm PldB performance at 400Hz. The size of fabricated MMIC PA is 4mm x3mm. These results closely match with design results. This MMIC DA Sl PA will be used as the unit cells to develop millimeter-wave transmitters for use in wideband wireless LAN systems.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.413-422
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• 2002

A novel photonic bandgap(PBG) structure is proposed and measured for wide bandgap and compact circuit applications. The proposed structure realizes the ultra-wideband bandgap(2-octave) characteristics by superposing two different PBG structures into a coupled double-plane configuration. A low pass filter fabricated using 3-period of the PBG cells shows 2-octave 10 ㏈ stopband from 4.3 to 16.2 ㎓ and 0.2 ㏈ insertion loss in the passband. Moreover, we confirmed that 44∼70 % size reduction can be achieved using the proposed PBG structures. We expect this novel double-plane PBG structure is widely used for compact and wideband circuit applications, such as compact high-efficiency power amplifiers using harmonic tuning techniques.

• ETRI Journal
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• v.40 no.6
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• pp.693-698
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• 2018

This paper presents a true-time delay (TTD) using a commercial $0.13-{\mu}m$ CMOS process for wideband phased-array antennas without the beam squint. The proposed TTD consists of four wideband distributed gain amplifiers (WDGAs), a 7-bit TTD circuit, and a 6-bit digital step attenuator (DSA) circuit. The T-type attenuator with a low-pass filter and the WDGAs are implemented for a low insertion loss error between the reference and time-delay states, and has a flat gain performance. The overall gain and return losses are >7 dB and >10 dB, respectively, at 2 GHz-18 GHz. The maximum time delay of 198 ps with a 1.56-ps step and the maximum attenuation of 31.5 dB with a 0.5-dB step are achieved at 2 GHz-18 GHz. The RMS time-delay and amplitude errors are <3 ps and <1 dB, respectively, at 2 GHz-18 GHz. An output P1 dB of <-0.5 dBm is achieved at 2 GHz-18 GHz. The chip size is $3.3{\times}1.6mm^2$, including pads, and the DC power consumption is 370 mW for a 3.3-V supply voltage.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.818-823
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• 2014

A high-gain wideband low noise amplifier (LNA) using $0.25-{\mu}m$ Gallium-Nitride (GaN) MMIC technology is presented. The LNA shows 8 GHz to 15 GHz operation by a distributed amplifier architecture and high gain with an additional common source amplifier as a mid-stage. The measurement results show a flat gain of $25.1{\pm}0.8dB$ and input and output matching of -12 dB for all targeted frequencies. The measured minimum noise figure is 2.8 dB at 12.6 GHz and below 3.6 dB across all frequencies. It consumes 98 mA with a 10-V supply. By adjusting the gate voltage of the mid-stage common source amplifier, the overall gain is controlled stably from 13 dB to 24 dB with no significant variations of the input and output matching.