1,721,328 research outputs found
A GaN-on-Si MMIC Power Amplifier with 10W Output Power and 35% Efficiency for Ka-Band Satellite Downlink
No full textThe design and experimental characterization of a Monolithic Microwave Integrated Circuits (MMICs) Power Amplifiers (PAs) specifically conceived for next generation Ka-band Very High Throughput Satellites (vHTS) are discussed. The chip has been implemented on a commercially available 100 nm gate length Gallium Nitride on Silicon (GaN-Si) process. The design was carried out accounting for the peculiarities of the application, therefore the selection of the devices' bias points and the matching network topologies was driven, and then accomplished, by carefully considering the thermal constraints of the technology, in order to keep the junction temperature of all devices below 160°C. The MMIC, based on a three stage architecture, has been fully characterized from 17.3 GHz to 20.2 GHz. In such a frequency range, it delivers an output power larger than 40 dBm with a power added efficiency peak higher than 40% and 22 dB of gain
Parasitic effects of the metallic towers on the characteristics of the broadcast antennas
Full text linkIn this article, we use a tool NEC (Numerical Electromagnetic Code) to model antenna on top of a tower structure. Simulation results for the parasitic effect of the tower on characteristics of broadcast DVB‐T (Digital Video Broadcasting Terrestrial) antenna such as input impedance, return loss, gain, front‐to‐back ratio and radiation patterns are reported. In addition, the effect of a nearby tower on antenna characteristics is studied. A 3D tower and broadband antenna in the UHF (470‐862) MHz band are constructed. The antenna works for both digital and analog TV with return loss (RL) ≥ 10 dB, fractional bandwidth of 87% and gain of 12.3 dBi at center frequency. The effective radiated power is calculated by mounting the antenna at each face of the tower to give a satisfactory coverage to a region around the antenna
A High Efficiency and Low Distortion 6 W GaN MMIC Doherty Amplifier for 7 GHz Radio Links
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A Design Approach to Maximize the Efficiency vs. Linearity Trade-Off in Fixed and Modulated Load GaN Power Amplifiers
No full textThis paper proposes a design method to minimize the phase distortion (AM/PM) in Gallium Nitride (GaN) Power Amplifiers (PAs), without significantly worsening other key features such as efficiency, amplitude distortion and gain. The design strategy consists in the adoption of a smart two-stage architecture, in which the driver stage is devised to act as a sort of “analogue AM/PM predistorter” for the final one. Accounting for the actual trend in PA solutions, the proposed approach has been fine-tuned to implement a two way class AB PA and a Doherty Power Amplifier (DPA) for backhaul radio links. Both circuits, realized on the same 0.25μm GaN technology and in monolithic form, have fully been characterized with continuous wave (CW) and modulated signals. At 7 GHz the DPA shows 38dBm of saturated output power and less than 3° of phase distortion, with a power added efficiency (PAE) higher than 41% in 6 dB of power back off. The class AB PA achieves almost the same level of saturated output power and maximum PAE, with an inevitable lower efficiency in back off operation, whereas the registered AM/PM is lower than 1.5°. Moreover, when tested with modulated signals, at 32dBm of average output power and without any digital predistortion, the DPA shows a spectral regrowth of around 36 dBc and a PAE of 40%, whereas the class AB PA achieves 40 dBc and 30%, respectively
Enhancing power efficiency of doherty power amplifiers using windowing based crest factor reduction technique
No full textThis paper investigates the performance of a Windowing Based Crest Factor Reduction (CFRWB) technique, to enhance the power efficiency of Radio Frequency (RF) power amplifiers. In particular, CFRWB is implemented on a Doherty Power Amplifier (DPA) in conjunction with Generalized Memory Polynomial (GMPDPD), and Volterra series based Digital Predistortion (VDPD) techniques. Key features like spectral regrowth, Peak to Average Power Ratio (PAPR) reduction, efficiency improvement and Error Vector Magnitude (EVM) have been used to measure the efficacy of the proposed method. Both simulation and experimental results show that the proposed combination of CFRWB technique with GMPDPD and VDPD is able to reduce the PAPR of the complex input signals by nearly 60%, with minimal degrading of the EVM and spectral regrowth. Moreover, such signal with reduced PAPR can be used to overdrive the DPA, allowing for a relevant average efficiency enhancement (i.e., up to 25%), while fulfilling the requirements of modern communication standards such as Wideband Code Division Multiple Access (WCDMA) and long-term evolution (LTE)
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