The Head of the Class

Eron, M.; Kim, Bumman; Raab, Frederick H.; Caverly, Robert H.; Staudinger, Joseph

doi:10.1109/mmm.2011.942725

Cited by 20 publications

(5 citation statements)

References 36 publications

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“…In the higher input voltage region, the peak amplifier starts operating, thereby, loading the carrier amplifier [32]. The peak amplifier output impedance reduces in this region towards the nominal value at highest output power, while the carrier amplifier output impedance goes from double towards the nominal value at highest output power [33]. This is depicted in Fig.…”

Section: Doherty Operationmentioning

confidence: 89%

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Zenteno

Isaksson

Händel

2015

IEEE Trans. Microwave Theory Techn.

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This paper analyzes the effects of load impedance mismatch in power amplifiers which linearity has been enhanced using various digital predistortion (DPD) algorithms. Two different power amplifier architectures are considered: a class AB and a Doherty amplifier and three model structures for the DPD model are compared: memoryless polynomial (MLP), general memory polynomial (GMP) and Kautz-Volterra functions (KV). This paper provides a sensitivity analysis of the linearized amplifiers under load mismatch conditions and reports the performance when dynamic parameter identification for the DPD is used to compensate for the changes in the load impedance. In general,power amplifiers linearity is sensitive to load impedance mismatch. Linearity may degrade as much as 10 dB (in normalized mean square error) according to the magnitude and the phase of the reflection coefficient provided by the load impedance. However, depending on the amplifier design, the sensitivity toload impedance mismatch varies. While the Doherty amplifier studied show significant linearity degradations in the in-band and out-of-band distortions, the out-of-band distortions of the studied class AB were less sensitive to the load impedance mismatch. In adaptive DPD schemes, the performance obtained in the MLP model does not benefit from the updating scheme and the performance achieved is similar to a static case, where no updates are made. This stresses the memory requirements in the predistorter. When employing the GMP and the KV models in an adaptive DPD scheme, they tackle to a larger extent the linearity degradations due to load impedance mismatch.

QC 20150123

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Section: Doherty Operationmentioning

confidence: 89%

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Zenteno

Isaksson

Händel

2015

IEEE Trans. Microwave Theory Techn.

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QC 20150123

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“…Besides the LINC approaches, there are many more forms of linearizing methods for power-efficient operation, including the Kahn technique, envelope tracking, the Doherty technique, feedback and feedforward linearization, and others with new techniques continuing to emerge (see [30] and references therein for a detailed discussion of linearization methods). Generally speaking, these methods rely on a combination of two or more amplifiers that focus on specific attributes of the signal being amplified and digital signal processing (DSP) to separate the signal into the requisite components.…”

Section: B Waveform Diversitymentioning

confidence: 99%

Radar Spectrum Engineering and Management: Technical and Regulatory Issues

et al. 2015

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| The radio-frequency (RF) electromagnetic spectrum, extending from below 1 MHz to above 100 GHz, represents a precious resource. It is used for a wide range of purposes, including communications, radio and television broadcasting, radionavigation, and sensing. Radar represents a fundamentally important use of the electromagnetic (EM) spectrum, in applications which include air traffic control, geophysical monitoring of Earth resources from space, automotive safety, severe weather tracking, and surveillance for defense and security. Nearly all services have a need for greater bandwidth, which means that there will be ever-greater competition for this finite resource. The paper explains the nature of the spectrum congestion problem from a radar perspective, and describes a number of possible approaches to its solution both from technical and regulatory points of view.These include improved transmitter spectral purity, passive radar, and intelligent, cognitive approaches that dynamically optimize spectrum use.

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“…Various efficiency‐boosting techniques have been developed and extensively investigated at the microwave range, such as class E , class‐F , class‐J , and so forth. Among these techniques, the class‐F and class‐F −1 (inverse F) PAs have been the leading candidates .…”

Section: Introductionmentioning

confidence: 99%

High‐efficiency GaN class‐F/class‐F⁻¹ power amplifiers with distributed L‐shaped parasitic‐compensation circuit

Cheng

Zhu

et al. 2015

Micro & Optical Tech Letters

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state-of-the-art VCOs. Although the fabricated VCO chip shows better phase noise than the references [4][5][6][7][8], the main achievement of this work is to obtain high-RF output power with high efficiency and high value of FOM PE , at least compared with the other VCO chips in the references [4][5][6][7][8] around the operating frequency of 1 GHz. CONCLUSIONA high-power and high-efficiency LC cross-coupled CMOS VCO is developed to be integrated into ADS-B transmitter. By operating in the borderline of voltage-limited and currentlimited mode and using custom designed diode-connected NMOS transistors as variable capacitors, the VCO delivers single-ended peak output power of 1.4 dBm and differential peak output power of 4.4 dBm at 1.097 GHz and maintains almost constant output power in the entire frequency tuning range of 120 MHz. Additionally, using diode-connected tail transistor, the VCO achieves core efficiency of 32.5% and the whole chip efficiency of 5.7%. The state-of-the-art performance comparison shows this CMOS VCO delivers highest reported output power with highest efficiency and highest FOM around 1 GHz operating frequency to the best of author's knowledge with good phase noise performance and desirable tuning range, thus shows the promising applications toward realizing highpower single-chip CMOS-based ADS-B transmitter.ABSTRACT: This article presents a straightforward parasiticcompensation design method for class-F and class-F 21 (inverse F) power amplifiers (PAs) based on a simple L-shaped transmission-line section. Design equations are presented and design procedures are elaborated. The fabricated PAs, operating at 2.14 GHz, deliver maximum power-added efficiency of 80.2% for the class-F mode and 79.1% for the class-F 21 mode, respectively.ABSTRACT: This article presents the image reconstruction results of measurement data from a preliminary test using the first-developed precision microwave tomography (MT) system operating at 3-6 GHz for medical diagnosis. A simple phantom is used in the MT system to verify the data validation. The measurement dataset has very different patterns owing to the significant contrast of dielectric properties according to the existence of a phantom in the sensing area of the illumination tank at microwave frequencies. Thus, it is possible to obtain the image reconstruction from this measurement data. The detailed results are presented and discussed.

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The Head of the Class

Cited by 20 publications

References 36 publications

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Radar Spectrum Engineering and Management: Technical and Regulatory Issues

High‐efficiency GaN class‐F/class‐F⁻¹ power amplifiers with distributed L‐shaped parasitic‐compensation circuit

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The Head of the Class

Cited by 20 publications

References 36 publications

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Output Impedance Mismatch Effects on the Linearity Performance of Digitally Predistorted Power Amplifiers

Radar Spectrum Engineering and Management: Technical and Regulatory Issues

High‐efficiency GaN class‐F/class‐F−1 power amplifiers with distributed L‐shaped parasitic‐compensation circuit

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Product

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High‐efficiency GaN class‐F/class‐F⁻¹ power amplifiers with distributed L‐shaped parasitic‐compensation circuit