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This paper presents a new type of a low-loss miniaturized coplanar-waveguide (CPW) transmission line (TL) by employing distributed loading, capacitors and inductors, in 0.18- $\mu \text{m}$ complementary metal–oxide–semiconductor (CMOS) technology. The capacitors are realized by vertical parallel plates made of vias, and a group of open stubs inserted to the signal line, whereas the inductors are realized by high impedance lines. Then, the proposed CPW-TL is employed to design a miniaturized millimeter wave ultra-wideband low-loss Wilkinson power divider/combiner (WPD/C). The proposed distributed loading results in reducing each WPD/C arm length by more than 50% without changing its characteristic impedance and insertion loss (IL). The design is fabricated in 0.18- $\mu \text{m}$ CMOS technology and tested. The measured results show a wideband performance from dc to 67 GHz with 1-dB IL and isolation greater than 15 dB from 36 to 67 GHz. In addition, the fabricated WPD/C achieves an excellent amplitude imbalance and phase imbalance of less than 0.16 dB and 0.45°, respectively. The core chip size is $336 \times 165\,\,\mu \text{m}^{2}$ , which is almost 32.8% compact compared to the recently proposed WPD in the same technology. [ABSTRACT FROM AUTHOR]

A frequency reconfigurable millimeter-wave (mm-wave) power amplifier (PA), which can be programmed to operate efficiently for a wide swathe of the spectrum, approaching an universal transmitter, can enable a wide range of novel applications in high-speed communication, sensing, and imaging. Classical techniques to allow large operating range either rely on broadband higher order output combining networks or tunable passives, both of which tradeoff directly with output power and efficiency. In this paper, we present an active impedance synthesis methodology that exploits the interaction of multiple unit PA cells in an asymmetrical non-isolated combiner to synthesize complex mm-wave impedances in a programmable fashion. This allows the interacting power cells to see their optimal load-pull impedances for high-efficiency frequency-reconfigurable operation in an efficient combiner network with no lossy variable passives. Compared to a symmetrical combiner, this enables the network to break the strong tradeoffs between output power, efficiency, and frequency reconfigurability, allowing it to achieve N times the Bode–Fano bound compared with an N-way symmetrical architecture. As a proof of concept, an integrated PA, which is in a 0.13- \mu \textm SiGe process, is demonstrated to achieve $P_{{{\text {sat}}}}$ of 23.6 dBm at a power-added efficiency (PAE) of 27.7% at 55 GHz with a frequency reconfigurable $P_{{\text {sat}},-1}$ sat 1 dB bandwidth of 25 GHz (40–65 GHz) and a PAE,−1 dB bandwidth of 20 GHz (40–60 GHz). Multi-Gbps data rates are demonstrated with non-constant envelope modulations across the frequencies 40–60 GHz. [ABSTRACT FROM PUBLISHER]

Two principal elements play a role in a wireless power beaming system: a high power radiation source as the transmitter and a rectifying antenna (rectenna) as an RF to DC converter at the receiving site. A millimeter wave power transmission is analyzed using transmission system and a W-band rectenna based on a low-barrier Schottky diode. A quasi-optical approach is presented here, using free-space Gaussian propagation and optical ABCD matrices for lenses. Experiments are made to estimate the optimal load resistance and power handling capability of a single rectifier. A low power W-band tunable solid-state source delivering 0.4 W CW power equipped by the focusing lenses is used to characterize the responsivity of the rectenna. A pulsed power gyrotron is used to identify the diode breakdown point. It was found that the RF-to-DC conversion efficiency corresponding to the optimal load of 200 Ω is about 20.5% while the maximum DC power converted by the diode with optimal load is about 15 mW before breakdown. [ABSTRACT FROM AUTHOR]

This paper presents a novel balun for a millimeter-wave power amplifier (PA) design to achieve high-power density in a 65-nm low-power (LP) CMOS process. By using a concentric winding technique, the proposed parallel combining balun with compact size accomplishes power combining and unbalance-balance conversion concurrently. For calculating its power combination efficiency in the condition of various amplitude and phase wave components, a method basing on S-parameters is derived. Based on the proposed parallel combining balun, a fabricated 60-GHz industrial, scientific, and medical (ISM) band PA with single-ended I/O achieves an 18.9-dB gain and an 8.8-dBm output power at 1-dB compression and 14.3-dBm saturated output power ( P ) at 62 GHz. This PA occupying only a 0.10-mm core area has demonstrated a high-power density of 269.15 mW/mm in 65 nm LP CMOS. [ABSTRACT FROM AUTHOR]

The benefits of organizing multichannel communications by fragmenting the data in bonded or in aggregated channels have been usually assessed at the media access control layer, being the network traffic the purpose of the studies. Despite the importance of the different kinds of channel organizations over the transmit signal peak-to average power ratio (PAPR) to size the back-off value of the power amplifier, little attention has been paid to it. In this paper the key aspect is the PAPR, which is fundamental to face transmitter designs optimizing the trade-off between linearity and the time-of-life of the batteries. The results are of interest not only in ad hoc cognitive radio networks, but also in some of the latest European Telecommunications Standards Institute and Institute of Electrical and Electronics Engineers standards supporting mobility in either wireless local area network environments or in cellular communications. A standardized radio link is used to model a realistic scenario to study different settings of the aggregate channels and to compare them with channel bonding alternatives. Besides, the suitability of some crest factor reduction techniques is here considered for different channel organizations. The results show how the channel organization (contiguous, regular and random spaced), either with bonded or aggregated strategies, affects the PAPR. [ABSTRACT FROM AUTHOR]

The potentialities of GaN monolithic technology for the growing microwave backhaul power amplifier market are discussed in this paper. To support this discussion, two GaN monolithic Doherty power amplifiers for 7 GHz backhaul applications are presented. They exhibit 5 W output power, with almost 10 dB gain and high efficiency at 7 dB output power back-off. In particular, one module has been optimized for maximum efficiency at center frequency (47% at 7 dB output power back-off), while the other for high efficiency on a larger bandwidth (15% fractional bandwidth). [ABSTRACT FROM AUTHOR]

In the 2008 IEEE Microwave Theory and Techniques Society International Microwave Symposium Digest version of our paper, recent advances in high power and efficiency space traveling-wave tube amplifiers for NASA's space-to-Earth communications are presented. The RF power and efficiency of a new K-band amplifier are 40W and 50% and that of a new Ka-band amplifier are 200 Wand 60%. An important figure-of-merit, which is defined as the ratio of the RF power output to the mass (W/kg) of a traveling-wave tube (TWT), has improved by a factor of 10 over the previous generation Ka-band devices. In this paper, a high power high efficiency Ka-band combiner for multiple TWTs, based on a novel hybrid magic-T waveguide circuit design, is presented. The measured combiner efficiency is as high as 90%. In addition, at the design frequency of 32.05 GHz, error-free uncoded binary phase-shift keying/quadrature phase-shift keying (QPSK) data transmission at 8 Mb/s, which is typical for deep-space communications, is demonstrated. Furthermore, QPSK data transmission at 622 Mb/s is demonstrated with a low bit error rate of 2.4 x 10-8, which exceeds the deep-space state-of-the-art data rate transmission capability by more than two orders of magnitude. A potential application of the TWT combiner is in deep-space communication systems for planetary exploration requiring transmitter power on the order of a kilowatt or higher. [ABSTRACT FROM AUTHOR]

A sheet-beam traveling-wave amplifier has been proposed as a high-power generator of radio frequency (RF) from 95 to 300 GHz, using a microfabricated RF slow-wave structure (Carlsten, 2002). The planar geometry of microfabrication technologies matches well with the nearly planar geometry of a sheet beam, and the greater allowable beam current leads to high-peak power, high-average power, and wide bandwidths. Simulations of nominal designs using a vane-loaded waveguide as the slow-wave structure have indicated gains in excess of 1 dB/mm, with extraction efficiencies greater than 20% at 95 GHz with a 120-kV, 20-A electron beam. We have identified stable sheet beam formation and transport as the key enabling technology for this type of device. Also, due to the high aspect ratio in the slow-wave structure, the RF coupling is complicated and requires multiple input and output couplers. The RF mode must be transversely flat over the width of the electron beam, which impacts both the vane design and the input and output coupling. We report on new insights on stable sheet-beam transport and RF mode control in the slow-wave structure. [ABSTRACT FROM PUBLISHER]