• ETRI Journal
• /
• v.31 no.3
• /
• pp.247-253
• /
• 2009

We propose a Ku-band driver and high-power amplifier monolithic microwave integrated circuits (MMICs) employing a compensating gate bias circuit using a commercial 0.5 ${\mu}m$ GaAs pHEMT technology. The integrated gate bias circuit provides compensation for the threshold voltage and temperature variations as well as independence of the supply voltage variations. A fabricated two-stage Ku-band driver amplifier MMIC exhibits a typical output power of 30.5 dBm and power-added efficiency (PAE) of 37% over a 13.5 GHz to 15.0 GHz frequency band, while a fabricated three-stage Ku-band high-power amplifier MMIC exhibits a maximum saturated output power of 39.25 dBm (8.4 W) and PAE of 22.7% at 14.5 GHz.

• Progress in Superconductivity and Cryogenics
• /
• v.7 no.1
• /
• pp.17-20
• /
• 2005

We has designed, fabricated, and measured a Single flux quantum (SFQ) toggle flip-flop (TFF). The TFF is widely used in superconductive digital electronics circuits. Many digital devices, such as frequency counter, counting ADC and program counter be used TFF Specially, a program counter may be constructed based on TFF We have designed the newly TFF and obtained high bias margins on test. In this work, we used two circuit simulation tools, WRspice and Julia, as circuit optimization tools. We used XIC for a layout tool. Newly designed TFF had minimum bias margins of +/- $37\%$ and maximum bias margins of +/-$37\%$(enhanced from +/- $37\%$). The designed circuits were fabricated by using Nb technology The test results showed that the re-optimized TFF operated correctly on 100kHz and had a very wide bias margins of +/- $53\%$.

• Applied Science and Convergence Technology
• /
• v.23 no.3
• /
• pp.145-150
• /
• 2014

MgO thin films were deposited by internal ICP-assisted reactive-magnetron sputtering with bipolar pulse bias on a substrate to suppress random arcs. Mg is reactively sputtered by a bipolar pulsed DC power of 100 kHz into ICP generated by a dielectrically shielded internal antenna. At a mass flow ratio of $Ar/O_2$ = 10 : 2 and an ICP/sputter power ratio of 1 : 1, optimal film properties were obtained (a powder-like crystal orientation distribution and a RMS surface roughness of approximately 0.42 nm). A bipolar pulse substrate bias at a proper frequency (~a few kHz) prevented random arc events. The crystalline preferred orientations varied between the (111), (200) and (220) orientations. By optimizing the plasma conditions, films having similar bulk crystallinity characteristics (JCPDS data) were successfully obtained.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.8
• /
• pp.1429-1435
• /
• 2010

In this paper, a double lorentz composite right left handed(DL-CRLH) transmission line is designed using defected ground structure (DGS) and varactor diodes. Previously, the diode has been adopted only selectively for one of parallel or series resonators, and the balanced frequency as well as triple band frequencies were fixed. However in the proposed DL-CRLH transmission line, the balanced frequency, where the resonant frequencies of the series-connected parallel resonator and shunt-connected series resonator are the same, is adjustable. In addition, the triple band frequencies are controlled, too. The measured balanced frequency varies between 3.42~4.8GHz according to the controlled bias voltage. Under the same bias condition for the balanced frequency, the adjusted frequencies are 2.22~2.77GHz, 3.7~5.2GHz, 7.32~8.23GHz, 3.42~4.8GHz, and 4.44~5.92GHz for the conditions that ${\beta}d=+0.5{\pi}$, $-0.5{\pi}$, 2nd $+0.5{\pi}$, ${\omega}_{\infty}$, and ${\omega}_o$, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.6
• /
• pp.560-566
• /
• 2004

In this paper, active frequency doubler with broadband characteristics from 6 ㎓ to 12 ㎓ was designed and fabricated using PHEMT. The designed frequency multiplier has a bias point near pinch-off and a proposed series RC circuit between bias line and input matching network far the improvement of stability. With 0 ㏈m input power, second harmonic of 1.7 ㏈m at 12 ㎓ -27.5 ㏈c suppression of 6 ㎓ fundamental, -18 ㏈c suppression of 18 ㎓ 3rd harmonic, and the 3 ㏈ output bandwidth of 1,8 ㎓ have been measured.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.5 s.347
• /
• pp.128-136
• /
• 2006

In this paper, design and implement 50W Doherty power amplifiers for 3GPP repeater and base station transceiver system. Efficiency improvement and high power property of ideal Doherty power amplifier is distinguishable; however bias control for implementation of Doherty(GDCHD) amplifier is difficult. To solve the problem, therefore, GDCHD(Gate and Drain Control Hybrid Doherty) power amplifier is embodied to drain bias adjustment circuit to Doherty power amplifier with gate bias adjustment circuit. Experiment result shows that $2.11{\sim}2.17\;GHz$, 3GPP operating frequency band, with 57.03 dB gain, PEP output is 50.30 dBm, W-CDMA average power is 47.01 dBm, and -40.45 dBc ACLR characteristic in 5MHz offset frequency band. Each of the parameter satisfied amplifier specification which we want to design. Especially, GDCHD power amplifier shows proper efficiency performance improvement in uniformity ACLR than Doherty power amplifier.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1996.06a
• /
• pp.159-160
• /
• 1996

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.1
• /
• pp.77-83
• /
• 2011

In this thesis, 50W Doherty amplifier was designed and implemented for Beyond 3G's repeater and base-station. Auxiliary amplifier of doherty amplifier was implemented by Gate bias control circuit. Though gate bias control circuit solved auxiliary's bias problem, output characteristics of doherty amplifier was limited. To enhance the output characteristic relativize Drain control circuit And To improve power efficiency make 3-way Doherty power amplifier. therefore, 3-way GDCD (Gate and Drain bias Control Doherty) power amplifier is embodied to drain bias circuit for General Doherty power amplifier. The 3-way GDCD power amplifier composed of matching circuit with chip capacitor and micro strip line using FR4 dielectric substance of specific inductive capacity(${\varepsilon}r$) 4.6, dielectric substance height(H) 30 Mills, and 2.68 Mills(2 oz) of copper plate thickness(T). Experiment result satisfied specification of amplifier with gains are 57.03 dB in 2.11 ~ 2.17 GHz, 3GPP frequency band, PEP output is 50.30 dBm, W-CDMA average power is 47.01 dBm, and ACLR characteristics at 5MHz offset frequency band station is -40.45 dBc. Especially, 3-way DCHD power amplifier showed excellence efficiency performance improvement in same ACLR than general doherty power amplifier.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.2
• /
• pp.87-91
• /
• 2008

In this paper, the adaptive chirp beamforming method is proposed to solve the bias problem in the direction-of-arrivals (DOAs) estimation of the wideband chirp signals which have an identical time-frequency parameter and are emanated from different directions. The source location bias results from the interferences impinging on the array from the other directions. The proposed method exploits the time-frequency structure of the chirp signal based on STMV (STeered Minimum Valiance) to improve the DOA estimation performance by minimizing the chirp interferences effectively. Simulation results show the DOA estimation performance achieved by the proposed method as compared to the conventional methods.

• Nuclear Engineering and Technology
• /
• v.54 no.2
• /
• pp.661-665
• /
• 2022

The 3 MeV proton irradiation effects on SiGe low noise amplifier (LNA) (NXP BGU7005) performance under different voltage supply VCC (0 V, 2.5 V) conditions were firstly experimental studied in this present work. The S parameters including S₁₁, S₂₂, S₂₁, 1 dB compression point and noise figure (NF) of the test samples under different bias voltage supply were measured and compared before and after 3 MeV proton irradiation. The total proton irradiation fluence was 1 × 10¹⁵ protons/cm². The maximum degradation quantities of the gain S₂₁ and NF of the test samples under zero bias are measured respectively 1.6 dB and 1.2 dB. Compared with the samples under 2.5 V bias supply, the maximum degradation of S₂₁ and NF are respectively 1.1 dB and 0.8 dB in the whole frequency band. It is noteworthy that the gain and NF of SiGe LNAs under zero-bias mode suffer enhanced degradation compared with those under normal bias supply. The key influence factors are discussed based on the correlation of the SiGe device and the LNA circuit. Different process of the ionization damage and displacement damage under zero-bias and 2.5 V bias voltage supply contributed to the degradation difference. The underlying physical mechanisms are analyzed and investigated.