Push-pull Power Amplifier Research Articles

Prof. Itoh's Contributions to Antennas [Awards

Prof. Tatsuo Itoh is a preeminent researcher, mentor, and educator, whose efforts have influenced many in the field of electromagnetics and microwave engineering. Although Prof. Itoh may be best known for numerical techniques and periodic/metamaterial structures, he has also left his mark in the antenna community. Some of Prof. Itoh's antenna-related works include antennas and arrays that integrate active components such as push–pull power amplifiers and coupled oscillators to enable efficient radiation, spatial power combining, and beamsteering; broadband planar quasi-Yagi antennas that produce highly directive end-fire radiation [S34]–[S35]; uniplanar-compact photonic bandgap (PBG)-enhanced high-gain antennas; retrodirective arrays that can reradiate an incoming signal toward the source without a priori knowledge of the arrival direction; and metamaterial antennas that support unconventional radiation characteristics such as broad spatial-angle frequency scanning and negative/zeroth-order mode radiations.

ISM 대역 응용분야에 사용되는 13.56 MHz 5kW RF 제너레이터 구현

논문은 ISM 밴드 응용분야에 사용되는 13.35 MHz, 5 kW RF 제너레이터의 구현에 대한 내용이다. 이 제너레이터의 구성은 드라이브증폭기와 LDMOS 1.25 kW 트랜지스터를 클래스 AB 푸쉬풀 증폭기로 구현한 모듈을 바탕으로 4개의 모듈을 윌킨슨 형태의 전송선로 변환기를 이용하여 결합하는 구조를 갖고 있다. 이 제너레이터는 선형성보다는 높은 출력과 효율을 얻는 것이 중요하며, 트랜지스터에서 발생하는 열은 워터 쿨링에 의한 수냉식 방법을 선택하여 외부로 배출하였다. 또한, 결합기와 저역통과 필터의 결합 그리고 출력 및 반사 신호를 검출하는 보호회로를 삽입하였다. 이렇게 구현된 RF 제너레이터는 포화 전력레벨 5.33 kW 출력에서 79 %의 효율을 얻었다. This paper describes implementation of a 13.56 MHz, 5 kW RF high power generator for ISM band applications. This RF generator consists of four LDMOS modules of 1.25kW class-AB push-pull power amplifier with drive amplifier and its outputs are combined by using Wilkinson type transmission-line transformers. Its generator has a high efficiency and output power better than linearity. In order to discharge power transistor heats, we used on water cooled copper plate. Also, these have a composite circuit of combiner and low-pass filter and safety circuit to detector over and reflected power. The RF generator has achieved a efficiency of 79 % at 5.33 kW of saturated power level experimentally.

Filtering push–pull power amplifier based on novel impedance transformers

A novel filtering push–pull power amplifier (PPPA), based on unbalanced-to-balanced impedance transformers, is presented for the first time. This novel impedance transformer can not only simplify the PPPA topology and miniaturise the overall circuit size, but also provide the bandpass filtering response and improve the second harmonic suppression performance. The proposed impedance transformers, which are constructed by two different C-type line resonators, can provide good impedance matching performance under the odd-mode excitation, while achieve high common mode suppression under the even-mode excitation. Finally, a PPPA is designed and fabricated with the centre frequency of 2.45 GHz and bandwidth of 200 MHz for WLAN application. Moreover, detailed explanation and measured results are demonstrated for verification.

A 60-GHz Power Amplifier With AM–PM Distortion Cancellation in 40-nm CMOS

This paper presents a complementary push-pull 60-GHz power amplifier (PA) in 40-nm CMOS. The proposed technique is used to mitigate the amplitude to phase modulation (AM-PM) distortion caused by the nonlinear input capacitance of an MOS transistor. By operating in deep class-AB mode, the back-off efficiency of the PA is improved without compromising gain. The proposed interstage transformer with two secondary windings enables right impedance transformation concurrently for the two separate transistors with independent biasing ability. The two-stage PA achieves a gain of 22.4 dB, power added efficiency (PAE) PAEMAX of 23%, and saturated output power ( $P_{\text {SAT}}$ ) of 16.4 dBm with 8% PAE at 6 dB back-off. With 35 dB of adjacent channel power ratio. Also a comparison with a common-source PA is presented, which shows its limitation in dealing with AM-PM distortion.

High‐efficiency CMOS push‐pull power amplifier with multilayer center‐tapped transformer

This paper describes the design of a push‐pull power amplifier (PA) with a center‐tapped transformer for transmitter applications on the 5.2‐GHz band using 0.18μm CMOS technology. The type of the proposed PA is based on a double‐ended push–pull (DEPP) configuration. DEPP has a simple construction with only transistors and transformers. The PA has reverse‐phased cascode‐connected transistors. The proposed transformer has a multilayer structure and was designed using electromagnetic field simulation. To achieve high power added efficiency (PAE), we assumed the optimized output impedance technique with a tunable impedance antenna. The PA has 13.2 dB linearity gain, 14.9 dBm 1‐dB compression point (P1dB), and 27.4% maximum PAE. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Piezoelectric Filter Module Used in Harmonics Elimination for High-Efficiency Piezoelectric Transformer Driving

Switching driving, such as pulse width modulation, has been used in many power circuits because of its high efficiency. However, given the capacitance of a piezoelectric transformer (PT) for high harmonics in a square waveform, using switching technology directly in a driver circuit is difficult without an inductance linked with the PT. This paper proposes a design of a piezoelectric filter module for eliminating harmonic frequencies in the driving of a PT. Compared with a traditional inductor filter, the performance, cost, and space advantages make the module a wiser choice. The particular design of several PFs fabricated on one piece of piezoelectric plate has future integration potential with the transformer. The third harmonic filtering experiment shows that the module exhibits excellent performance on the elimination of harmonics and improvement of the whole converter's efficiency, making the large inductor for wide-range damping of harmonics unnecessary. Efficiency analyses for a simplified push–pull power amplifier model prove the existence of an optimum output waveform for a tradeoff consideration on the circuit efficiency and driving complexity of a PT. This study offers detailed guidance for the future development of novel converter circuits.

An 85-W Multi-Octave Push–Pull GaN HEMT Power Amplifier for High-Efficiency Communication Applications at Microwave Frequencies

This paper proposes a design methodology for multi-octave planar push–pull power amplifiers (PPPAs) to tackle the challenges associated with the integration of planar balanced to unbalanced transformers (baluns) with packaged transistors characterized by significant parasitics. This methodology relies on carefully selecting the balun’s placement and adding external matching networks to separately control the odd- and even-mode impedances presented to the power amplifier (PA) to ensure high-efficiency operation over a broad range of frequencies. Proper second harmonic impedances are obtained by placing the balun in close proximity to the transistors’ terminals and repurposing the packaged transistors’ leads into a coupled-line with a high coupling coefficient. Furthermore, adequate odd-mode terminations are realized using broadband matching networks at the unbalanced side of the baluns. Following this methodology, an 85-W PPPA was designed using off-the-shelf packaged gallium–nitride high electron-mobility transistors. The fabricated PA demonstrated drain efficiency and output power above 45% and 46.5 dBm, respectively, over the frequency band spanning from 0.45 to 1.95 GHz. Furthermore, the fabricated PA was successfully linearized using digital predistortion when driven with single- and multi-band modulated signals. Overall, the fabricated PA had the best reported power, efficiency, bandwidth, and second harmonic rejection combination for a multi-octave PPPA designed with input and output baluns using packaged off-the-shelf transistors.

A high output power V-band GaAs HEMT push–pull power amplifier using meandering baluns technology

A broadband, high saturation output power 0.15-μm gate length GaAs pseudomorphic high-electron mobility transistor push-pull V-band power amplifier has been demonstrated using meandering balun designs. Two meandering low-loss planar three-coupled-line baluns were used to form push–pull mechanism for both stages. The meandering baluns provide 180° differential outputs from the applied single-ended input at the V-band and the size was reduced for 23% compared to traditional design. The proposed push–pull amplifier achieved a peak small-signal gain of 16.8 dB at 58 GHz, a 3 dB bandwidth of 55–62 GHz, and a peak power added efficiency of 13.8%.

A Full X‐Band Power Amplifier with an Integrated Guanella‐Type Transformer and a Predistortion Linearizer In 0.18‐µM CMOS

ABSTRACTA full X‐band push‐pull power amplifier (PA) with predistortion linearizer is developed in tsmcTM 0.18‐µm CMOS technology. The broadband performance is achieved by using transformers including a differential Guanella‐type transmission line transformer and two magnetically coupled transformers. The linearity of PA is enhanced by feedback topology and the use of predistortion linearizer. Over full X‐band from 8 to 12 GHz, the saturated power and maximum power‐added efficiency are higher than 21.3 dBm and 16.19%, respectively. The performances of output power at 1‐dB compression point and power‐added efficiency (PAE) at P1dB are significantly improved by an output power of 2.2 dBm and a PAE of 12.1%, which contributes to power back‐off operation for the application of linear modulation. The chip area, including pads, is 1.05 mm2. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2229–2232, 2013

Investigation of Push-Pull Microwave Power Amplifiers Using an Advanced Measurement Setup

In this letter, we investigate the influence of the output balun for realization of wideband and efficient microwave push-pull power amplifiers (PAs). For this, a push-pull GaN-HEMT PA operating between 1-3 GHz without an output balun has been implemented and a novel push-pull harmonic load-pull measurement setup that allows arbitrary balanced fundamental and second harmonic loads to be presented to the push-pull PA is proposed. The measurement results illustrate that the efficiency may be degraded up to 25% if improper common mode harmonic impedances are presented by the balun. The proposed approach allows the PA and balun to be investigated separately and is therefore expected to be an important tool for further research on balun and PA structures suitable for high efficiency and wideband push-pull applications at microwave frequencies.

Push-Pull Class-${\rm E}_{\rm M}$ Power Amplifier for Low Harmonic-Contents and High Output-Power Applications

This paper introduces a push-pull class-EM power amplifier for achieving low harmonic contents and high output power. By applying the push-pull configuration of the class-EM power amplifier, the proposed amplifier achieves an extremely lower total harmonic distortion (THD) and about four times higher output power than the conventional single class-EM power amplifier. Design curves of the proposed amplifiers for satisfying the class-EM ZVS/ZDVS/ZCS/ZDCS conditions are given. A design example is shown along with the PSpice-simulation and experimental waveforms for 1-MHz amplifier, considering the MOSFET drain-to-source nonlinear parasitic capacitances, MOSFET switch-on resistances, and equivalent series resistance of the inductors. The waveforms from the PSpice simulation and circuit experiment satisfied all the switching conditions, which has shown the accuracy of the design curves given in this paper and validated the effectiveness of the push-pull class-EM power amplifier.

A Novel Formulation for High Efficiency Modes in Push-Pull Power Amplifiers Using Transmission Line Baluns

Push-pull power amplifiers (PAs) operating at HF through to GHz frequencies typically employ a transmission line balun structure. This letter demonstrates that their performance characteristics in high efficiency PA applications are critically different from conventional transformers. For the first time, the effect of the even-mode open-circuit termination on the output waveforms is measured. A novel mathematical formulation is proposed to describe the time-domain waveforms by defining the harmonic impedance environment in terms of odd and even mode excitation rather than tuned harmonics. Experimental verification using harmonic load-pull measurements showed good agreement with the theoretical waveforms generated from factorized waveform expressions.

Design of a broadband power amplifier using an optimized feedback network

AbstractThis article presents a systematic design method for ultra broadband power amplifiers using an optimized feedback network. Based on the analysis using the network parameters for the open‐loop circuit and feedback network, a design and optimization procedure was established. To make the gain response as flat as possible throughout the broad operating frequency band, the optimized component values of the feedback network were found using an optimization program which was built based on the least‐mean‐square‐error algorithm in MATLAB. Single‐ended broadband power amplifiers were implemented to verify the optimization results for various target gains, as well as source and load impedance sets. One of the single‐ended amplifiers was selected for use as part of the push–pull power amplifier which includes broad‐band 1:1 transmission line transformers. For the operational bandwidth from 8 to 800 MHz, the ultra broad‐band push–pull power amplifier exhibited a flat gain response of ±0.331 dB from 17.2 dB, a P1dB of more than 40.5 dBm, and high PAE from 26.7 to 45 % at each P1dB point. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2846–2851, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26372

Ultrabroadband Linear Power Amplifier Using a Frequency-Selective Analog Predistorter

This brief presents an ultrabroadband (2- to 600-MHz band) linear power amplifier using a compact frequency-selective analog predistorter, which includes a capacitor having an optimized capacitance and a biased Schottky diode connected in series. It is shunted at the input of the main amplifier and has a frequency-selective third-order intermodulation generation capability using its optimized capacitance. A two-stage push-pull power amplifier, which has an ultrabroadband operation range from 2 to 600 MHz, was implemented and linearized using the proposed analog predistorter. It exhibited high 1-dB compression point (P1 dB) and power-added efficiency characteristics of over 43 dBm and 32% at each P1 dB for the entire operating band, respectively. At an average output power level of 36 dBm for the two-tone signal input, which has a tone spacing of 1 MHz, its third-order intermodulation distortion over the entire band is no higher than -39.1 dBc after linearization, as compared with -34.2 dBc before linearization.

High-Efficiency Push–Pull Power Amplifier With High Operation Voltage

A highly efficient push-pull class D power amplifier (PA) with a high operation voltage is presented. The high voltage is realized by stacking dc biases of two push-pull amplifiers through the virtual ground point, while the radio frequency powers are series combined. The drain supply voltage is increased to 44V, which is double of the rated bias voltage (22V) of the active devices. The LDMOS PA provides an output power of 40.6dBm with a power-added efficiency (PAE) of 58.7% at 836.5MHz. Each push-pull amplifier provides 38-dBm output with a PAE of 64%

Low-Harmonic Push–Pull Class-E Power Amplifier With a Pair of <emphasis emphasistype="italic">LC</emphasis> Resonant Networks

This paper proposes a novel push-pull Class-E series-parallel resonant power amplifier (PA), which parallels two basic one-inductor, one-capacitor Class-E high-efficiency switching-mode tuned PA (Sokal, 1981) circuits. This proposed topology utilizes a push-pull scheme to realize sinusoidal output voltage. The previously published Class-E circuits (Sokal, 1981) can be implemented in a very simplified circuit. However, the simplified circuit is only appropriate for applications in which the harmonic content of output is not an important criterion. The proposed amplifier with two series-parallel resonant load networks will allow sinusoidal output voltage to be achieved by associating with the positive and negative quasi-sinusoidal waveforms. The complementarily activated configuration will provide continuous high-ripple-frequency input-current waveforms; this approach significantly reduces electromagnetic interference and requires very little filtering. With the symmetry of the push-pull Class-E circuit, there is the additional benefit that the even harmonics are suppressed at the load, and thus there are fewer harmonic distortions. However, each switch is symmetrically driven with a duty ratio of less than 0.5 to meet the nominal Class-E operating conditions, which leads to a narrower operating frequency variation. A prototype of the proposed PA shows over 95% efficiency at 48-V input, with 18-W output and an operating frequency of 900 kHz

Augmented hammerstein predistorter for linearization of broad-band wireless transmitters

In this paper, an augmented lookup-table-based Hammerstein predistorter is proposed for the first time in order to further improve the pre-correction capability of the traditional Hammerstein predistorter in the context of broad-band high-power wireless transmitters. The predistorter scheme consists of two separate modules, and its parameters are determined in two steps, which are: 1) static predistorter identification and then 2) dynamic part identification. The performance assessment of the newly proposed predistorter is carried out on a wireless transmitter prototype, which includes an L-band push-pull GaAs field-effect transistor 45-dBm peak-envelope power amplifier. Moreover, one- and three-carrier Third-Generation Partnership Projects frequency-division duplex wide-band code-division multiple-access signals are used as test signals to verify the robustness of this novel predistorter under different bandwidth signals. The linearized transmitter prototype output spectrum demonstrates noticeable superiority of the proposed augmented predistorter in suppressing the spectrum regrowth caused by the memory effects in comparison to the traditional Hammerstein predistorter.

A wideband compact parallel-strip 180/spl deg/ Wilkinson power divider for push-pull circuitries

A Wilkinson power divider with a differential output implemented in parallel-strip-line (PSL) is proposed. Taking full advantages of the PSL technology and a three-stage cascaded design, more than 170% impedance and isolation bandwidths are obtained. Inherent to the PSL structure, the 180deg differential output is frequency-independent. A class-B push-pull power amplifier employing the devised concept is designed, showing a peak efficiency of 44% over a 4-GHz bandwidth. Without exploiting any extra and external low-pass filters, the proposed design can produce startling second-harmonic suppressions (more than 50dB) over the whole working dynamics and operated bandwidth

Bifurcation analysis of stabilization circuits in an L-band LDMOS 60-W power amplifier

In this letter, the global stability analysis of an L-band push-pull power amplifier is presented. The analysis is carried out for the amplifier operating in different modes, such as Class AB, Class B, and Class E/F, considering variations in the bias voltages, the input power and the input frequency. After determination of the oscillation mode, three different stabilization techniques are applied and compared: feedback resistors, neutralization capacitors, and odd-mode stabilization resistor. The element values of each stabilization network, ensuring a stable behavior for all the operating conditions, are calculated with a bifurcation-analysis technique. Good agreement is found between measured and simulated results.

A fully integrated 5.3-GHz 2.4-V 0.3-W SiGe bipolar power amplifier with 50-/spl Omega/ output

A radio frequency power amplifier for 4.8-5.7 GHz has been realized in a 0.35-/spl mu/m SiGe bipolar technology. The balanced two-stage push-pull power amplifier uses two on-chip transformers as input-balun and for interstage matching. Further, it uses three coils for the integrated LC-output balun and the RF choke. Thus, the power amplifier does not require any external components. At 1.0-V, 1.5-V, and 2.4-V supply voltages, output powers of 17.7 dBm, 21.6 dBm, and 25 dBm are achieved at 5.3 GHz. The respective power-added efficiencies (PAE) are 15%, 22%, and 24%. The small-signal gain is 26 dB. The output 1-dB compression point at 2.4 V is 22 dBm with a PAE of 14%.