https://calhoun.nps.edu/bitstream/10945/24839/1/singlesidebandtr00elli.pdf

Single sideband transmission by envelope elimination and restoration.

Gas breakdown at microscale dimensions has been of great interest to the microelectromechanical systems (MEMS) and plasma communities for nearly 15 years as the first reports of deviations from traditional theory began to emerge. Since those first reports, a significant amount of work has investigated why gas breakdown deviates from the classic Paschen’s Law when the dimensions are in the range of 1–10 µm. Nearly universally, these deviations that form the so-called modified Paschen’s curve have been attributed to electron field emission, where electrons directly tunnel from the cathode into the gas due to the very high electric fields at microscale dimensions. Furthermore, because of ionization in the gas gap, field emission is enhanced by positive ions and thus is inherently coupled to the gas and discharge dynamics. Progress in understanding the mechanisms and physics of this process has in turn led to new ideas and devices that capitalize on the high surface-to-volume ratio in microscale dimensions and take advantage of cathode emission processes. This topical review summarizes and analyzes the numerous experimental, computational and analytical works on breakdown at microscale dimensions, discusses implications and new areas emerging in microscale devices that take advantage of field emission and presents perspectives looking ahead at new opportunities for field emission-driven microplasmas.

https://iopscience.iop.org/article/10.1088/0022-3727/47/50/503001/pdf

Microscale gas breakdown: ion-enhanced field emission and the modified Paschen’s curve

In order to satisfy the power thirst of communication devices in the imminent fifth generation era, wireless charging techniques have attracted much attention both from the academic and industrial communities Although the inductive coupling and magnetic resonance-based charging techniques are indeed capable of supplying energy in a wireless manner, they tend to restrict the freedom of movement By contrast, radio frequency (RF) signals are capable of supplying energy over distances, which are gradually inclining closer to our ultimate goal—charging anytime and anywhere Furthermore, transmitters capable of emitting RF signals have been widely deployed, such as TV towers, cellular base stations, and Wi-Fi access points This communication infrastructure may indeed be employed also for wireless energy transfer (WET) Therefore, no extra investment in dedicated WET infrastructure is required However, allowing RF signal-based WET may impair the wireless information transfer (WIT) operating in the same spectrum Hence, it is crucial to coordinate and balance WET and WIT for simultaneous wireless information and power transfer, which evolves to integrated data and energy communication networks (IDENs) To this end, a ubiquitous IDEN architecture is introduced by summarizing its natural heterogeneity and by synthesizing a diverse range of integrated WET and WIT scenarios Then the inherent relationship between WET and WIT is revealed from an information theoretical perspective, which is followed by the critical appraisal of the hardware enabling techniques extracting energy from RF signals Furthermore, the transceiver design, resource allocation, and user scheduling as well as networking aspects are elaborated on In a nutshell, this treatise can be used as a handbook for researchers and engineers, who are interested in enriching their knowledge base of IDENs and in putting this vision into practice

/pdf/integrated-data-and-energy-communication-network-a-27pizx991f.pdf

Integrated Data and Energy Communication Network: A Comprehensive Survey

The application of metal-organic frameworks (MOFs) as a sensing layer has been attracting great interest over the last decade, due to their uniform properties in terms of high porosity and tunability, which provides a large surface area and/or centers for trapping/binding a targeted analyte. Here we report the fabrication of a highly sensitive humidity sensor that is based on composite thin films of HKUST-1 MOF and carbon nanotubes (CNT). The composite sensing films were fabricated by spin coating technique on a quartz-crystal microbalance (QCM) and a comparison of their shift in resonance frequencies to adsorbed water vapor (5–75% relative humidity) is presented. Through optimization of the CNT and HKUST-1 composition, we could demonstrate a 230% increase in sensitivity compared to plain HKUST-1 film. The optimized CNT-HKUST-1 composite thin films are stable, reliable, and have an average sensitivity of about 2.5 × 10−5 (Δf/f) per percent of relative humidity, which is up to ten times better than previously reported QCM-based humidity sensors. The approach presented here is facile and paves a promising path towards enhancing the sensitivity of MOF-based sensors.

/pdf/the-quest-for-highly-sensitive-qcm-humidity-sensors-the-3gpaq88gt0.pdf

The quest for highly sensitive QCM humidity sensors: the coating of CNT/MOF composite sensing films as case study

Due to the severe cost pressure of consumer electronics, a migration to an advanced nanoscale CMOS processes, which is primarily developed for fast and low-power digital circuits operating at low supply voltages, is necessary, but it forces wireless RF transceivers to exploit more and more digital circuitry These basic CMOS properties tend to coerce the design of wireless functions towards the digital domain where transistors are utilized as switches rather than current sources Within the past decade, there have been tremendous efforts towards implementing fully-digital or digitally-intensive RF transmitters in which they demonstrate transmitter designs that operate from baseband up to the pre-power amplifier (PA) stage entirely in the digital domain In view of this digitalization, the RF transmitter modulator, being the nearest to the antenna as it converts digital baseband modulation samples into an RF waveform, is considered the most critical building block of the transmitter, and it can be in the form of either a polar, Cartesian (I/Q), or an outphasing topology For wide modulation bandwidths, due to their direct linear summation of the in-phase (I) and quadrature-phase (Q) signals and thus the avoidance of the bandwidth expansion, Cartesian modulators are substantiated as the most appropriate choice over their polar or outphasing counterparts Since the effective modulating sample resolution is the utmost important parameter as it directly impacts the achievable dynamic range, linearity, error vector magnitude (EVM), noise floor, and out-of-band spectral emission, this thesis proposes a wideband, high-resolution, all-digital orthogonal I/Q radio-frequency digital-to-analog (RF-DAC) Chapter 1 briefly provides an overview of the conventional RF radio building blocks It is discussed that contemporary RF transceivers must support most of multi-mode/multiband communication standards such as Wi-Fi, Bluetooth, and Fourth Generation (4G) of 3GPP cellular In Chapter 2, four types of RF transmitter architectures have been briefly described The analog I/Q modulators are the most straightforward and widely employed RF transmitters They are later replaced by analog polar counterparts to address their poor power efficiency and noise performance On the other hand, in the analog polar RF transmitters, their related amplitude and phase signals must be aligned or spectral regrowth is inevitable Utilizing digitally intensive polar RF transmitters mitigates the latter alignment issue Nonetheless, polar transmitters suffer from an additional issue that is related to their nonlinear conversion of in-phase and quadrature-phase signals into the amplitude and phase representation Therefore, the polar RF transmitters are not able to manage very large baseband bandwidth of the most stringent communication standards, therefore, reusing I/Q modulators based on digitally intensive implementation appears to be a reasonable approach to resolve this issue The digital I/Q RF transmitters, however, suffer again from inadequate power efficiency Moreover, the combination of in-phase and quadrature phase paths must be orthogonal to produce an undistorted-upconverted-modulated RF signal In Chapter 3, a novel all-digital I/Q RF modulator is described Employing an upconverting RF clock with a 25% duty cycle ensures the orthogonal summation of Ipath and Qpath, which avoids nonlinear signal distortion It was clarified that electric summing of I and Q digital unit array switches is the most appropriate I/Q orthogonal summation approach Moreover, to address all four quadrants of the constellation diagram, the differential quadrature upconverting RF clocks must be utilized In addition, it was explained that employing switches instead of utilizing current sources leads to superior noise performance of the all-digital I/Q transmitter In Chapter 4, a novel 2×3-bit all-digital I/Q (Cartesian) RF transmit modulator is implemented which operates as an RF-DAC The modulator performs based on the concept of orthogonal summing, which is introduced and elaborated in Chapter 3 It is based on a time-division duplexing (TDD) manner of an orthogonal I/Q addition By employing this method, a very simple and compact design featuring high-output power, power-efficiency and low-EVM has been realized The resolution of the experimental RF-DAC presented in this work is only 3-bit (including one sign bit), but it will be demonstrated in the following chapters that the resolution can be increased to 8–12 bits in an unequivocal manner for utilization in multi-standard wireless applications In Chapter 5, the system design considerations of the proposed high-resolution, wideband all-digital I/Q RF-DAC are discussed It is demonstrated that the upsampling clock frequency (fCKR), DRAC resolution (Nb), and memory length (lmem) are three important parameters that affect the dynamic performance of the proposed RF-DAC Based on system level simulation results and the limitation in implementing the RF-DAC test-chip, they are designated as fCKR=300 MHz, Nb=12 bit, and lmem=8 k-word The effect of these parameters on the in-band as well as out-of-band performance of RF-DAC are investigated It is concluded that exploiting 13 bits of resolution for quadrature baseband signals is sufficient to meet the most stringent communication requirements In Chapter 6, the theory and the design procedure of an innovative, differential, orthogonal power combining network, which is employed in the proposed all-digital modulator, is thoroughly explained It is demonstrated that, in order to maintain an orthogonal operation between the in-phase and quadrature-phase paths, the effect of the power combiner on the in-phase and quadrature-phase paths must be considered, otherwise, the linear summation will not occur As a result, the EVM and linearity performance will diminish The power combiner consists of a transformer balun as well as its related programmable primary and secondary shunt capacitors In order to achieve high efficiency at full power of operation, a class-E type matching network is adopted and subsequently modified in order to obtain a minimum modulation error A switchable cascode structure is exploited to mitigate a reliability issue as well as to perform a mixer operation Moreover, utilizing a switchable cascode structure also improves the isolation between quadrature paths Furthermore, it is explained that the power combiner efficiency is primarily related to the transformer balun efficiency A procedure is introduced in order to design an efficient, compact balun transformer Also, it is explained that the RF-DAC operates as a class-B power amplifier at the power back-off levels As a result, its performance in the power back-off region is lowered In Chapter 7, the implemented wideband, 2×13-bit I/Q RF-DAC-based all-digital modulator realized in 65-nm CMOS is presented Employing the orthogonal I/Q combining approach which is proposed in Chapter 3 guarantees the isolation between in-phase and quadrature-phase paths The 4×f0 off-chip single-ended clock is converted to a differential version employing an on-chip transformer The wide swing, low phase noise, high-speed dividers are incorporated to translate the 4×f0 differential clock to the fundamental frequency of f0 In the meantime, the complementary quadrature sign bit is used to address four quadrants of the related constellation diagram The 25% differential quadrature clocks are generated using logic-AND operation between 2×f0 differential clock and f0 differential quadrature clocks The 12-bit DRAC is implemented employing a segmentation approach, which consists of 256 MSB and 16 LSB thermometer unit cells The layout arrangement of the DRAC unit cell proves to be very crucial It was concluded that the vertical layout would be the most appropriate selection The LO leakage and I/Q image rejection technique as well as two DPD memoryless techniques of AM-AM/AM-PM and constellation mapping are introduced, which will be extensively utilized in the measurement segment In Chapter 8, the high-resolution wideband 2×13-bit all-digital I/Q transmitter, which was introduced in Chapter 7, is thoroughly measured First, the chip is tested in continuouswave mode operation It is demonstrated that, with a 13V supply and, of course, an on-chip power combiner, the RF-DAC chip generates more than 21dBm RF output power within a frequency range of 136–251 GHz The peak RF output power, overall system, and drain energy efficiencies of the modulator are 228 dBm, 34%, and 42%, respectively The measured static noise floor is below -160 dBc/Hz The digital I/Q RF modulator demonstrates an IQ image rejection and LO leakage of -65 dBc and -68 dBc, respectively The RF-DAC could be linearized employing either of the two digital predistortion (DPD) approaches: memoryless polynomial or a lookup table Its linearity is examined utilizing 4/16/64/256/1024-QAM baseband signals while their related modulation bandwidth can be as high as 154 MHz Using AM-AM/AM-PM DPD improves the linearity by more than 25 dB while the measured EVM is better than -28 dB Moreover, the constellation-mapping DPD is applied to the RF-DAC which improves linearity by more than 19 dB These numbers indicate that this innovative concept is a viable option for the next generations of multi band/multi-standard transmitters The realized demonstrator can perform as an energy-efficient RF-DAC in a stand-alone digital transmitter directly (eg, for WLAN) or as a pre-driver for high-power basestation PAs Chapter 9 draws the conclusions of the this thesis work and provides recommendations for future research and directions in the field of all-digital RF transmitters for wireless communication applications

All-Digital I/Q RF-DAC

This paper presents an all-digital class-G quadrature switched-capacitor power amplifier (Q-SCPA) implemented in 65 nm CMOS. It combines in-phase ( I ) and quadrature ( Q ) signals on a shared capacitor array. The I / Q signals are digitally weighted and combined in the charge domain. Quadrature summation results in a 3 dB signal loss; Hence the Q-SCPA utilizes a class-G dual-supply architecture to improve efficiency at backoff. Unlike polar/EER counterparts, the Q-SCPA requires no wideband phase modulator or delay matching circuitry. The Q-SCPA delivers a peak output power of 20.5 dBm with a peak PAE of 20%. It is measured with a 10 MHz, 64 QAM LTE signal, and achieves an ACLR of $ , with an ${\bf EVM} 4%-rms.

/pdf/a-quadrature-switched-capacitor-power-amplifier-k5mvjdhobn.pdf

A Quadrature Switched Capacitor Power Amplifier

This paper presents an all-digital multiphase switched capacitor power amplifier (MP-SCPA) implemented in a 130-nm CMOS. Quadrature architectures suffer reduced output power and efficiency owing to the combination of out-of-phase signals. The MP architecture reduces the phase difference between the basis vectors that are combined, and hence the output power and efficiency are greatly improved. Sixteen clocks with identical adjacent phase separations are produced by a phase generator with each phase’s relative amplitude weighted on the top plate of a capacitor array and combined on a common bottom plate, resulting in linear amplification. The MP-SCPA delivers a peak output power $P_{\mathrm{ out}}$ of 26 dBm with a peak system efficiency (SE) of 24.9%. When amplifying a long-term evolution signal at 1.85 GHz, the average $P_{\mathrm{ out}}$ and the SE are 20.9 dBm and 15.2%, respectively, with an Adjacent Channel Leakage Ratio (ACLR) < −30 dBc and error vector magnitude of 3.5% rms using a 2-D digital predistortion.

A Multiphase Switched Capacitor Power Amplifier

This paper presents a 13-b C-2C split-array (SA) multiphase switched-capacitor power amplifier (SAMP-SCPA) implemented in 65-nm CMOS. The SAMP-SCPA was designed for 16-b resolution to offer extra states for linearization/calibration using digital pre-distortion (DPD). Resolution limits for SA SCPAs are presented. The SAMP-SCPA allows for the improvement of the SCPA resolution while minimizing the impact on the input power required driving it. A prototype SAMP-SCPA, occupying 0.85 mm $\times $ 2 mm, delivers a peak output power of 24 dBm with a peak system efficiency (SE) of 40% at 1.8 GHz. When amplifying a long-term evolution (LTE) signal, the average output power and SE are 18.8 dBm and 21.6%, respectively, with an adjacent channel leakage ration (ACLR) < −30 dBc and error vector magnitude (EVM) of 2.65% rms. The increased resolution allows output power to be traded off for improved linearity and a low power mode demonstrates an EVM as low as 1% rms.

Split-Array, C-2C Switched-Capacitor Power Amplifiers

In this paper a wideband, high-power amplifier that achieves an output power of 20 W with a bandwidth greater than one octave in the L and S bands is presented. Two ~10 W Class AB PAs are implemented with Gallium Nitride-high electron mobility transistor devices and a low loaded-Q matching network to achieve wideband performance. High power added efficiency (PAE) is achieved by combining outphased saturated power amplifiers using a wideband isolated combiner. We introduce new analysis detailing proper selection of the isolation resistance in isolated outphasing combiners. The impedance transforming Wilkinson combiner is designed to interface the system with a 50- $\Omega $ load. The L-S band (1.2~2.5GHz) amplifier was simulated, fabricated, and characterized. The fabricated HPA provides a peak output power of 43 dBm, gain of >15 dB with a peak PAE of >40% across the band. A 10 MHz, 64 QAM, long-term evolution signal is measured and achieves ACLR < −30 dBc, EVM = 4.8%-rms at an average output power and efficiency of 39.3 dBm and 33.1%, respectively.

Wideband Techniques for Outphasing Power Amplifiers

https://www.rpi.edu/%7Ewangg/publications/Biaxial%20CdTe%20on%20CaF2%20growth%20on%20amorphous.pdf

Wen Yuan

Papers

A Quadrature Switched Capacitor Power Amplifier

A Multiphase Switched Capacitor Power Amplifier

Split-Array, C-2C Switched-Capacitor Power Amplifiers

Wideband Techniques for Outphasing Power Amplifiers

Biaxial CdTe/CaF2 films growth on amorphous surface