• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.5
• /
• pp.947-954
• /
• 2009

This paper proposed a new balanced power amplifier using the reflected input of conventional balanced power amplifiers composed of branch line hybrid coupler. In general, the single-ended amplifier in balanced amplifiers does not have the perfect matching, so the reflected input power, in other words the leakage power, is terminated conventionally at the isolation port of hybrid coupler. However in this work, the leakage power is injected into the auxiliary amplifier, and its output power is combined to the output power of balanced amplifier. Therefore output power, efficiency, and 2-tone IMD3 performances of the proposed balanced amplifier are highly improved compared to the conventional balanced amplifier. For the verification of the proposed balanced amplifier, a conventional balanced amplifier and the proposed balanced amplifier are designed, fabricated and measured, and the measured results are compared. The proposed balanced amplifier shows the improvement in the output power(Pout), power added efficiency (PAE), and 2-tone IMD3 by 3dB, 5.2%, and $5{\sim}10dBc$, respectively, from the measurement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.1
• /
• pp.68-75
• /
• 2012

The load-insensitivity of the balanced power amplifier(PA) for W-CDMA handset applications is analyzed. The load impedances of the two parallel amplifiers in the balanced PA depending on the output load mismatch are mathematically calculated and with the result, the phase of reflection coefficient at which the linear output power is severely degraded is investigated. From the analysis, we proposed that the linearity of the balanced PA at the phase can be improved by properly increasing the transistor size and thus, multiple balanced PA's with different transistor size are designed and simulated. The simulation result showed that the balanced PA with larger transistor size has improved linear output power under VSWR=4:1.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.4
• /
• pp.143-152
• /
• 2016

In this paper, a MMIC double balanced mixer that can be applied to the tele-communication band is designed and LO power optimization for the mixer is discussed. The chip of the MMIC double-balanced mixer is fabricated on GaAs substrate with the size of $4{\times}4mm^2$. Optimization study of LO power for the MMIC double-balanced mixer proposed in this paper is conducted for the Input IP3 (IIP3) regarding on the linearity of the input signal. When LO power level of+16 dBm is applied to the mixer, IIP3 is obtained to be approximately 23.2 dBm, which is the most outstanding characteristic.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.5
• /
• pp.606-612
• /
• 2012

A highly efficient multi-mode balanced power amplifier(PA) structure is proposed for W-CDMA handset applications. The proposed PA has 2-stage amplifier configuration and the stage-bypass and load impedance switching techniques were applied to enhance power efficiency at medium power level as well as low output power level. Using the two techniques, four highly efficient power modes were realized. To demonstrate the usefulness of the proposed structure, a GaAs HBT balanced PA module was designed, fabricated, and measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.8
• /
• pp.851-856
• /
• 2010

This paper presents an efficiency enhancement for the balanced power amplifier using DBS(Dynamic Bias Switching) method which dynamically provides the power amplifier with two bias voltage levels according to the input envelope signal. In order to apply the dynamic biases to each side of the balanced power amplifier, two switching stages are adopted. Using an OFDM signal with a bandwidth of 20 MHz and a PAR(Peak to Average Ratio) of 8.5 dB, 6 % of PAE(Power-Added Efficiency) is improved at an output power of 42.5 dBm.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.5
• /
• pp.492-500
• /
• 2013

A balanced forward-flyback converter for high efficiency and high power factor using a foward and flyback converter topologies is proposed in this paper. The conventional AC/DC flyback converter can achieve a good power factor but it has the high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the forward and flyback converters during switch turn-on and turn-off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input voltage, the core loss and volume of the transformer can be minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• Proceedings of the KIPE Conference
• /
• 1998.10a
• /
• pp.797-801
• /
• 1998

This paper presents a balanced 3/1 supply scheme for electric railway. By employing an active filter, the current of the three-phrase delivery system is balanced while the load is single phrase, which makes it possible for the traction system to behave like a pure-resistance load, with unity power factor and no harmonics. Simulation results are present to verify the scheme's topology and control strategies.

• ETRI Journal
• /
• v.31 no.5
• /
• pp.598-600
• /
• 2009

A highly efficient and compactly integrated balanced power amplifier (PA) for W-CDMA handset applications is presented. To overcome the size limit of a typical balanced PA, a bulky input divider is integrated into a PA MMIC, and a complex output network is replaced with simple lumped-element networks. For efficiency improvement at the low output power level, one of the two amplifiers in parallel is deactivated and the other is partially operated with corresponding load impedance optimization. The implemented PA shows excellent average current consumption of 34.5 mA in urban and 56.3 mA in suburban environments, while exhibiting very good load-insensitivity under condition of VSWR=4:1.

• Proceedings of the KIPE Conference
• /
• 1997.07a
• /
• pp.233-238
• /
• 1997

An important assumption for the active power filter design using instantaneous power theory and the d-q transformation method in a 3-phase power system is based on balanced 3-phase system. However, under pratical conditions, the 3-phase power system can not be continuously balanced due to unbalanced loading. In this paper, a method to control the 3-phase active power filer using instantaneous power theory and the d-q transformation under unbalanced power system is presented and the theoretical results are verified by simulated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.11
• /
• pp.1262-1270
• /
• 2007

In this paper, we propose a new distortion cancellation mechanism for a balanced power amplifier structure using the carrier cancellation loop of a feedforward and post-distortion technique. The proposed cross post-distortion balanced linear amplifier can reduce nonlinear components as much as the conventional feedforward amplifier through the output dynamic range and broad bandwidth. Also the proposed system provides higher efficiency than the feedforward. The capacities of power amplifier and error power amplifier in the proposed system are analyzed and compared with those of feedforward amplifier. Also the operation mechanisms of the three kind loops are explained. The proposed cross post-distortion balanced linear power amplifier is implemented at the IMT-2000($f_0=2.14\;GHz$) band. With the commercial high power amplifiers of total power of 240 W peak envelope power fer base-station application, the adjacent channel leakage ratio measurement with wideband code division multiple access 4FA signal shows 18.6 dB improvement at an average output power of 40 dBm. The efficiency of fabricated amplifier Improves about 2 % than the conventional feedforward amplifier.