Showing papers on "Amplifier published in 2021"

Switchmode RF and Microwave Power Amplifiers

Abstract: Combining solid theoretical discussions with practical design examples, this book is an essential reference on developing RF and microwave switchmode power amplifiers. With this book you will be able to: * Design high-efficiency RF and microwave power amplifiers on different types of bipolar and field-effect transistors using well-known and novel theoretical approaches, nonlinear simulation tools, and practical design techniques * Design any type of high-efficiency switchmode power amplifiers operating in Class D or E at lower frequencies and in Class E or F and their subclasses at microwave frequencies, with specified output power * Understand the theory and practical implementation of load-network design techniques based on lumped and transmission-line elements * Combine multi-stage Doherty architecture and switchmode power amplifiers to significantly increase efficiency of the entire radio transmitter * Learn the different types of predistortion linearization techniques required to improve the quality of signal transmission in a nonlinear amplifying system New to this edition: . Comprehensive overview of different Doherty architectures which are, and will be used in modern communication systems to save power consumption and reduce costs . A new chapter on analog and digital predistortion techniques . Coverage of broadband Class-F power amplifiers, high-power inverse Class-F power amplifiers for WCDMA systems, broadband Class-E techniques *Unique focus on switchmode RF and microwave power amplifiers that are widely used in cellular/wireless, satellite and radar communication systems and which offer major power consumption savings *Complete coverage of the new Doherty architecture which offers major efficiencies and savings on power consumption *Balances theory with practical implementatation, avoiding a cookbook approach, enabling engineers to develop better designs *Trusted content from leading figures in the field with a Foreword of endorsement by Zoya Popovic

Low-chirp isolator-free 65-GHz-bandwidth directly modulated lasers

Abstract: Today, in the face of ever increasing communication traffic, minimizing power consumption in data communication systems has become a challenge. Direct modulation of lasers, a technique as old as lasers themselves, is known for its high energy efficiency and low cost. However, the modulation bandwidth of directly modulated lasers has fallen behind those of external modulators. In this Article, we report wide bandwidths of 65–75 GHz for three directly modulated laser design implementations, by exploiting three bandwidth enhancement effects: detuned loading, photon–photon resonance and in-cavity frequency modulation–amplitude modulation conversion. Substantial reduction of chirp (α < 1.0) as well as isolator-free operation under a reflection of up to 40% are also realized. A fast data transmission of 294.7 Gb s−1 over 15 km of a standard single-mode fibre in the O-band is demonstrated. This was achieved without an optical fibre amplifier due to a high laser output power of 13.6 dBm. Directly modulated semiconductor lasers are shown to be able to operate with bandwidths exceeding 65 GHz thanks to a cavity design that harnesses photon–photon resonances.

Efficient erbium-doped thin-film lithium niobate waveguide amplifiers.

Abstract: Lithium niobate on insulator (LNOI) is an emerging photonic platform with great promise for use in future optical communications, nonlinear optics, and microwave photonics. An important integrated photonic building block, active waveguide amplifiers, however, are still missing in the LNOI platform. Here, we report an efficient and compact waveguide amplifier based on erbium-doped LNOI waveguides, achieved using a sequence of erbium-doped crystal growth, ion slicing, and lithography-based waveguide fabrication. Using a compact 5 mm long waveguide, we demonstrate an on-chip net gain of >5dB for 1530 nm signal light with a relatively low pump power of 21 mW at 980 nm. The efficient LNOI waveguide amplifiers could become an important fundamental element in future lithium niobate photonic integrated circuits.

Duobinary modulation/predistortion techniques effects on high bit rate radio over fiber systems

Abstract: The work has presented duobinary modulation and predistortion techniques for the radio over fiber system enhancement for achieving security level. Duobinary modulation technique has more compact modulated spectral linewidth with standard non return to zero modulation code. Different NRZ/RZ rectangle shape employed that are namely exponential rectangle shape (ERS), and Gaussian rectangle shape (GRS) for different transmission bit rates. Switching bias voltage, and switching RF voltage based LiNbO 3 modulator are changed to measure the performance parameters of the radio over fiber (RoF) system. Predistortion technique improves the linearity of transmitter amplifiers and it is considered as a power efficiency technique. The optimum values of the Q-factor, data error rate (BER), electrical power, signal gain, noise figure, and light signal/noise ratio are achieved with 8 Volt for both switching biases/switching RF signal at 100 GHz. Signal quality/BER and electrical power after the receiver enhancement ratio by using this technique at different RF signal frequencies.

Simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case

Abstract: This study has demonstrated the simulative and analytical methods of bidirectional EDFA amplifiers in optical communication links in the optimum case. The output power, max. Q factor and light signal/noise ratio variations are clarified with pump power variations at the bidirectional amplification EDFA amplifier for the previous/proposed models at optimum EDFA length of 8 m. As well as the output power and max. Q factor variations with EDFA amplifier length variations are demonstrated at the bidirectional amplification EDFA amplifier for the previous/proposed models at various pump power levels. The optimum operation efficiency case is observed at 8 m EDFA amplifier length and 120 mW pumping power.

III/V-on-lithium niobate amplifiers and lasers

Abstract: We demonstrate electrically pumped, heterogeneously integrated lasers on thin-film lithium niobate, featuring electro-optic wavelength tunability.

Wideband 23.5–29.5-GHz Phased Arrays for Multistandard 5G Applications and Carrier Aggregation

Abstract: This article presents a 23.5–29.5-GHz $8\times 8$ phased array for wideband multistandard applications. The array is based on wideband high-performance $2\times 2$ transmit/receive (TRX) quad-beamformer chips with 6 bit of phase control and 8 bit of gain control. The antenna is designed using a stacked-patch structure combined with a two-stage impedance matching network to enhance its bandwidth. The $8\times 8$ phased array achieves an effective isotropic radiated power (EIRP) of 54.8 dBm at P1dB with a 3-dB bandwidth of 23.5–30.5 GHz and can scan to ±60° in the azimuth plane and +/40° in the elevation plane with excellent patterns with a single-point calibration at 27 GHz. Measured error vector magnitude (EVM) for a 64-QAM 200 and 800-Mbaud waveforms result in a system EVM of 5% (−26 dB) in the TX mode at an average EIRP of 46–47 dBm at 24.5–29.5 GHz. Also, the wideband array is capable of 16-QAM 24-Gb/s links with an EVM <16% over all scan angles. An interband carrier aggregation (CA) system is also demonstrated with the wideband array using 200-Mbaud 64-QAM waveforms with 25- and 29-GHz carriers. The phased-array phase and amplitude settings are chosen such that the 25- and 29-GHz waveforms are radiating simultaneously at the same angle with low scan loss, resulting in an efficient system. Also, the out-of-band third-order intermodulation products generated by the power amplifier on each element are filtered out by the antenna. CA measurements with up to 50° scan angles are demonstrated with low EVM. To the best of our knowledge, this is the first demonstration of CA in millimeter-wave fifth-generation (5G) systems.

Sub-thermionic, ultra-high-gain organic transistors and circuits

Abstract: The development of organic thin-film transistors (OTFTs) with low power consumption and high gain will advance many flexible electronics. Here, by combining solution-processed monolayer organic crystal, ferroelectric HfZrOx gating and van der Waals fabrication, we realize flexible OTFTs that simultaneously deliver high transconductance and sub-60 mV/dec switching, under one-volt operating voltage. The overall optimization of transconductance, subthreshold swing and output resistance leads to transistor intrinsic gain and amplifier voltage gain over 5.3 × 104 and 1.1 × 104, respectively, which outperform existing technologies using organics, oxides and low-dimensional nanomaterials. We further demonstrate battery-powered, integrated wearable electrocardiogram (ECG) and pulse sensors that can amplify human physiological signal by 900 times with high fidelity. The sensors are capable of detecting weak ECG waves (undetectable even by clinical equipment) and diagnosing arrhythmia and atrial fibrillation. Our sub-thermionic OTFT is promising for battery/wireless powered yet performance demanding applications such as electronic skins and radio-frequency identification tags, among many others.

Convolutional Neural Network for Behavioral Modeling and Predistortion of Wideband Power Amplifiers.

Abstract: Power amplifier (PA) models, such as the neural network (NN) models and the multilayer NN models, have problems with high complexity. In this article, we first propose a novel behavior model for wideband PAs, using a real-valued time-delay convolutional NN (RVTDCNN). The input data of the model is sorted and arranged as a graph composed of the in-phase and quadrature (I/Q) components and envelope-dependent terms of current and past signals. Then, we created a predesigned filter using the convolutional layer to extract the basis functions required for the PA forward or reverse modeling. Finally, the generated rich basis functions are input into a simple, fully connected layer to build the model. Due to the weight sharing characteristics of the convolutional model's structure, the strong memory effect does not lead to a significant increase in the complexity of the model. Meanwhile, the extraction effect of the predesigned filter also reduces the training complexity of the model. The experimental results show that the performance of the RVTDCNN model is almost the same as the NN models and the multilayer NN models. Meanwhile, compared with the abovementioned models, the coefficient number and computational complexity of the RVTDCNN model are significantly reduced. This advantage is noticeable when the memory effects of the PA are increased by using wider signal bandwidths.

Asymmetrical Load Modulated Balanced Amplifier With Continuum of Modulation Ratio and Dual-Octave Bandwidth

Abstract: This article presents a new load-modulation power amplifier (PA) architecture—asymmetrical load-modulated balanced amplifier (ALMBA). It is for the first time discovered that the control amplifier (CA) of LMBA can be designed with arbitrary load modulation (LM) ratio by offsetting the symmetry of two sub-amplifiers (BA1 and BA2) in the balanced topology. The rigorous analytical derivation reveals a unification of the quadrature-coupler-based LM PA theory, which inclusively covers the recently reported LMBA within this generalized framework. Through pseudo-Doherty (PD) biasing of the asymmetric BA1 & BA2 (peaking) and the CA (carrier) combined with proper amplitude and phase controls, the optimal LM behaviors of three amplifiers can be achieved independently overextended power back-off range and ultrawide RF bandwidth. Importantly, the LM of CA effectively mitigates the over-driving issue imposed on symmetrical PD-LMBA, leading to enhanced overall reliability and linearity. Based on the proposed theory, an RF-input PD-ALMBA is designed and implemented using commercial GaN transistors. The developed prototype experimentally demonstrates dual-octave bandwidth from 0.55 to 2.2 GHz, which is the widest bandwidth ever reported for load-modulation PAs. The measurement exhibits an efficiency of 49–82% for peak output power and 40–64% for 10-dB OBO within the design bandwidth. When stimulated by a 20-MHz long-term evolution (LTE) signal with 10.5-dB peak to average power ratio (PAPR), an average efficiency of 47–63% is measured over the entire bandwidth at an average output power around 33 dBm.

Radiofrequency transistors based on aligned carbon nanotube arrays

Abstract: The development of next-generation wireless communication technology requires integrated radiofrequency devices capable of operating at frequencies greater than 90 GHz. Carbon nanotube field-effect transistors are promising for such applications, but key performance metrics, including operating frequency, at present fall below theoretical predictions. Here we report radiofrequency transistors based on high-purity carbon nanotube arrays that are fabricated using a double-dispersion sorting and binary liquid interface aligning process. The nanotube arrays exhibit a density of approximately 120 nanotubes per micrometre, a maximum carrier mobility of 1,580 cm2 V−1 s−1 and a saturation velocity of up to 3.0 × 107 cm s−1. The resulting field-effect transistors offer high d.c. performance (on-state current of 1.92 mA µm−1 and peak transconductance of 1.40 mS μm−1 at a bias of −0.9 V) for operation at millimetre-wave and terahertz frequencies. Transistors with a 50 nm gate length show current-gain and power-gain cutoff frequencies of up to 540 and 306 GHz, respectively, and radiofrequency amplifiers can exhibit a high power gain (23.2 dB) and inherent linearity (31.2 dBm output power of the third-order intercept point) in the K-band (18 GHz). Transistors based on arrays of aligned carbon nanotubes can exhibit cutoff frequencies of up to 540 GHz, and could be further scaled for operation at millimetre-wave and terahertz frequencies.

1kW 1mJ 8-channel ultrafast fiber laser

Abstract: An ultrafast fiber chirped-pulse amplifier comprising 8 coherently combined amplifier channels is presented. The laser delivers 1 kW average power at 1 mJ pulse energy and 260 fs pulse duration. Excellent beam quality and low noise performance are confirmed. The laser has proven suitable for demanding scientific applications. Further power scaling is possible right away using even more amplifier channels

Photo thermal effect graphene detector featuring 105 Gbit s-1 NRZ and 120 Gbit s-1 PAM4 direct detection.

Abstract: One of the main challenges of next generation optical communication is to increase the available bandwidth while reducing the size, cost and power consumption of photonic integrated circuits. Graphene has been recently proposed to be integrated with silicon photonics to meet these goals because of its high mobility, fast carrier dynamics and ultra-broadband optical properties. We focus on graphene photodetectors for high speed datacom and telecom applications based on the photo-thermo-electric effect, allowing for direct optical power to voltage conversion, zero dark current, and ultra-fast operation. We report on a chemical vapour deposition graphene photodetector based on the photo-thermoelectric effect, integrated on a silicon waveguide, providing frequency response >65 GHz and optimized to be interfaced to a 50 Ω voltage amplifier for direct voltage amplification. We demonstrate a system test leading to direct detection of 105 Gbit s−1 non-return to zero and 120 Gbit s−1 4-level pulse amplitude modulation optical signals. The fast carrier dynamics and ultra-broadband optical properties of graphene make it suitable for optical communications. Here, the authors demonstrate a photo-thermo-electric graphene photodetector integrated on a Si waveguide featuring 105 Gbit s−1 non-return to zero and 120 Gbit s−1 4-level pulse amplitude modulation direct detection.

Bismuth doped fibre amplifier operating in E- and S- optical bands

Abstract: Bismuth-doped fibre amplifiers offer an attractive solution for expanding the bandwidth of fibre-optic telecommunication systems beyond the current C-band (1530-1565 nm). We report a bismuth-doped fibre amplifier in the spectral range from 1370 to 1490 nm, with a maximum gain exceeding 31 dB, and a noise figure as low as 4.75 dB. The developed system is studied for forward, backward, and bi-directional pumping schemes and three different signal power levels. The forward pumping scheme demonstrates the best performance in terms of the achieved noise figure. The developed amplifier can be potentially used as an in-line amplifier with >20dB gain in the spectral band from 1405 to 1460 nm.

A Ka -Band MMIC LNA in GaN-on-Si 100-nm Technology for High Dynamic Range Radar Receivers

Abstract: A Ka -band monolithic low-noise amplifier (LNA) with high gain and high dynamic range (DR) has been designed and implemented in a 100-nm gallium nitride (GaN)-on-Si technology. The LNA is designed as the first stage of a high DR receiver in an frequency modulated continuous wave (FMCW) radar for the detection of small drones. The three-stage monolithic microwave integrated circuit (MMIC) LNA has a linear gain of 26 dB and a noise figure (NF) of 2 dB in the frequency band 33–38 GHz. The output 1-dB compression point (P1dB) and output IP3 at 37 GHz are 20 and 28.4 dBm, respectively. To our knowledge, this combination of NF, gain, and DR performance represents the state of art in this frequency band.

Active Reconfigurable Intelligent Surface: Fully-Connected or Sub-Connected?

Abstract: To overcome the “multiplicative fading effect” introduced by passive reconfigurable intelligent surface (RIS), the concept of active RIS has been recently proposed to amplify the radiated signals. However, the existing fully-connected architecture of active RIS consumes high power due to the additionally integrated active components. To address this issue, we propose the sub-connected architecture of active RIS. Different from fully-connected architecture, where each element integrates a dedicated power amplifier, in the sub-connected architecture, multiple elements control their phase shifts independently but share a same power amplifier, which significantly reduces the number of power amplifiers for power saving at the cost of fewer degrees of freedom (DoFs) for beamforming design. Fortunately, our analysis reveals that performance loss introduced by the sub-connected architecture is slight, indicating that it can achieve much higher energy efficiency (EE). Furthermore, we formulate the EE maximization problem in the active RIS-aided system for both architectures and develop a corresponding joint beamforming design. Simulation results verify the proposed sub-connected architecture as an energy-efficient realization of active RIS.

Millimeter-Wave Power Amplifier Integrated Circuits for High Dynamic Range Signals

Abstract: The next-generation 5G and beyond-5G wireless systems have stimulated a substantial growth in research, development, and deployment of mm-Wave electronic systems and antenna arrays at various scales. It is also envisioned that large dynamic range modulation signals with high spectral efficiency will be ubiquitously employed in future communication and sensing systems. As the interface between the antennas and transceiver electronics, power amplifiers (PAs) typically govern the output power, energy efficiency, and reliability of the entire wireless systems. However, the wide use of high dynamic range signals at mm-Wave carrier frequencies substantially complicates the design of PAs and demands an ultimate balance of energy efficiency and linearity as well as other PA performances. In this review paper, we will first introduce the system-level requirements and design challenges on mm-Waves PAs due to high dynamic range signals. We will review advanced active load modulation architectures for mm-Wave PAs and power devices. We will then introduce recent advances in mm-Wave PA technologies and innovations with several design examples. Special design considerations on mm-Wave PAs for phased array MIMOs and high mm-Wave frequencies will be outlined. We will also share our vision on future technology trends and innovation opportunities.

7.1 kW coherent beam combining system based on a seven-channel fiber amplifier array

Abstract: Coherently combining of seven-channel narrow-linewidth, linear-polarized, kW-level power all-fiber amplifiers has been successfully demonstrated by using the stochastic parallel gradient descent (SPGD) algorithm. The seven polarization-maintained fiber amplifiers are tiled by a collimator array with a high lenslet filling factor (~95%). Total emitting power is ~8 kW, and ~7.1 kW combined output power is achieved and the contrast of the far-field intensity pattern is measured to be ~86% when the system is in the closed loop. This work could provide practical reference on scaling the output power of the tiled aperture coherent beam combining system.

70 mJ nonlinear compression and scaling route for an Yb amplifier using large-core hollow fibers.

Abstract: In this Letter, we investigate the energy-scaling rules of hollow-core fiber (HCF)-based nonlinear pulse propagation and compression merged with high-energy Yb-laser technology, in a regime where the effects such as plasma disturbance, optical damages, and setup size become important limiting parameters. As a demonstration, 70 mJ 230 fs pulses from a high-energy Yb laser amplifier were compressed down to 40 mJ 25 fs by using a 2.8-m-long stretched HCF with a core diameter of 1 mm, resulting in a record peak power of 1.3 TW. This work presents a critical advance of a high-energy pulse (hundreds of mJ level) nonlinear interactions platform based on high energy sub-ps Yb technology with considerable applications, including driving intense THz, X-ray pulses, Wakefield acceleration, parametric wave mixing and ultraviolet generation, and tunable long-wavelength generation via enhanced Raman scattering.

6.78-MHz Wireless Power Transfer With Self-Resonant Coils at 95% DC–DC Efficiency

Abstract: Megahertz-frequency inductive wireless power transfer holds the promise of compact and efficient wireless power transfer. Unfortunately, due to high-frequency losses in wide-bandgap semiconductors and low- $Q$ high-frequency coil designs, these systems are universally less efficient, on a dc–dc basis, than wireless power systems operating at conventional frequency regimes. This letter describes the design considerations for inductive wireless power transfer systems operating at 6.78 MHz. With a novel high-frequency resonant amplifier topology, a high- $Q$ self-resonant coil structure, and a better understanding of $C_{oss}$ losses in wide-bandgap power semiconductors, we demonstrate 6.78- MHz wireless power transfer systems that achieve 95% dc–dc efficiency at power levels up to and beyond 1 kW.

Demonstration of a Pulsed G-Band 50-W Traveling Wave Tube

Abstract: This letter presents the research progress of a pulsed G-band 50 W traveling wave tube (TWT) with pencil beam focused by periodic permanent magnet (PPM). Three approaches have been combined to improve the tube’s operation performances including setting the operating point near the cutoff frequency, using the folded waveguide (FWG) slow wave structure (SWS) with modified circular bends (MCBs), and adopting phase velocity tapering (PVT) technique. The measured output power can be over 50 W at 5% duty cycle with a bandwidth of 3.6 GHz when the beam voltage is 24.25 kV and the beam current is 59 mA. Corresponding electronic efficiency and gain are higher than 3.5% and 35 dB, respectively. The results provide a demonstration of a compact terahertz amplifier with high power, high electronic efficiency and significant bandwidth.

Perspective on traveling wave microwave parametric amplifiers

Abstract: Quantum-limited microwave parametric amplifiers are genuine key pillars for rising quantum technologies and, in general, for applications that rely on the successful readout of weak microwave signals by adding only the minimum amount of noise allowed by quantum mechanics. In this Perspective, after providing a brief overview on the different families of parametric microwave amplifiers, we focus on traveling wave parametric amplifiers, underlining the key achievements of the last few years and the present open challenges. We also discuss possible new research directions beyond amplification such as exploring these devices as a platform for multi-mode entanglement generation and for the development of single photon detectors.

A Broadband Linear Ultra-Compact mm-Wave Power Amplifier With Distributed-Balun Output Network: Analysis and Design

Abstract: This article presents a broadband power amplifier (PA) with a distributed-balun output network that provides the PA optimum load impedance over a wide bandwidth. The proposed output network comprises two coupled-line sections and absorbs the device output capacitance. It employs a scalable coupled-line modeling approach that captures both the magnetic (inductive) and electric (capacitive) couplings between windings with fewer parameters and supports a rapid design process. Closed-form design solutions, design space limitations, bandwidth limits, and design tradeoffs are derived and analyzed comprehensively. Its extension to differential output and common-mode response is also discussed in detail. As a proof of concept, a prototype PA is implemented for multiband fifth-generation (5G) applications in 45-nm SOI CMOS. With no biasing retuning or network reconfiguration, the PA consistently achieves >19.1 dBm $P_{\mathrm {sat}}$ , >37.3% peak power-added efficiency (PAE), 17.8–19.6 dBm $P_{\mathrm {1dB}}$ , and 36.6%–44.3% PAE $_{P\mathrm {1dB}}$ over 24–40 GHz, verifying the truly wideband large-signal matching. The PA demonstrates 5G new radio (NR) frequency range 2 (FR2) modulation signals over 24–42 GHz, covering n257/n258/n260 5G bands. For 5G NR FR2 800-MHz 2-CC 64-QAM signals (11.78-dB PAPR), the PA achieves 11.3-dBm/16.6% average $P_{\mathrm {out}}$ /PAE with −25.1-dB rms EVM at 28-GHz and 10.2-dBm/13.6% average $P_{\mathrm {out}}$ /PAE with −25.1-dB rms EVM at 37 GHz.

Overcoming the quantum limit of optical amplification in monolithic waveguides.

Abstract: Optical amplifiers are essential in numerous photonic applications. Parametric amplifiers, relying on a nonlinear material to create amplification, are uniquely promising as they can amplify without generating excess noise. Here, we demonstrate amplification based on the third-order nonlinearity in a single chip while, in addition, reporting a noise figure significantly below the conventional quantum limit when operated in phase-sensitive mode. Our results show the potential of nanophotonics for realizing continuous-wave parametric amplification that can enable applications in optical communications, signal processing, and quantum optics across a wide range of frequencies.

A 1.16-V 5.8-to-13.5-ppm/°C Curvature-Compensated CMOS Bandgap Reference Circuit With a Shared Offset-Cancellation Method for Internal Amplifiers

Abstract: This article introduces an accurate current-mode bandgap reference circuit design with a novel shared offset compensation scheme for its internal amplifiers. This bandgap circuit has been designed to operate over a very wide temperature range from −40 °C to 150 °C. Its output voltage is 1.16 V with a 3.3-V supply voltage. A multi-section curvature compensation method alleviates the error from the bipolar junction transistor’s base–emitter nonlinear voltage dependence on temperature. The bandgap reference circuit contains two operational amplifiers that are utilized to generate proportional-to-absolute-temperature (PTAT) and complementary-to-absolute-temperature (CTAT) current sources. With the implementation of the described shared offset-cancellation methodology, the simulated output inaccuracy introduced by the amplifier is kept to a 5 $\sigma $ offset within ±4.6 $\mu \text{V}$ while allowing to conserve die size and power consumption by preventing that each amplifier is accompanied by its own active auxiliary offset-cancellation circuit. Designed and fabricated in a 130-nm CMOS process technology, the bandgap reference has a measured output voltage shift of less than 1 mV over a −40 °C to 150 °C temperature range and an overall variation of ±8.2 mV across seven measured samples without trimming.

A High-Power Broadband Multi-Primary DAT-Based Doherty Power Amplifier for mm-Wave 5G Applications

Abstract: Silicon-based millimeter-wave (mm-Wave) power amplifiers (PAs) with high power and high peak/back-off efficiency are highly desired to efficiently amplify multi-Gb/s 5G NR signals. This article presents a fully integrated high-power broadband linear Doherty PA with multi-primary distributed-active-transformer (DAT) power combining. We introduce a transformer-based impedance inverter for active load modulation and a multi-primary DAT structure for hybrid series and parallel power combining. Based on this, we propose a transformer-based Doherty combiner with more design freedom and a multi-primary DAT-based Doherty PA for simultaneous active load modulation and low-loss power combining. The EM simulation results demonstrate that the proposed DAT-based Doherty output network achieves very symmetric and balanced load impedances among all the main and auxiliary PA ports. As a proof of concept, a 24–30-GHz prototype PA is implemented in a 0.13- $\mu \text{m}$ SiGe BiCMOS process. The PA achieves 30.4% PAEmax, 28.3-dBm $P_{\mathrm {sat}}$ , 30.2% PAE at 26.8-dBm $P_{\mathrm {1\,dB}}$ , and 21.2% PAE at 6-dB back-off from $P_{\mathrm {sat}}$ at 28 GHz. Modulation measurement with single-carrier 64-QAM signals and 5G NR FR2 orthogonal frequency-division multiplexing (OFDM) signals has been demonstrated. For a 200-MHz 1-CC 5G NR FR2 64-QAM signal, the PA achieves 18.1-dBm Pavg and 13.8% PAEavg with −25.1-dB rms EVM at 28 GHz.

Design of a Ka-Band Cascode Power Amplifier Linearized With Cold-FET Interstage Matching Network

Abstract: A Ka-band CMOS cascode power amplifier (PA) linearized with a cold-FET-based interstage matching network is presented, which is designed in a 65-nm CMOS process. Since it is difficult to make a cascode PA matched to the optimum output and input impedances at high frequencies, a matching network has to be introduced at the node between the common-source (CS) and common-gate (CG) stages. The cold-FET-based matching network improves the linearity and the input and output impedance matchings, which is analyzed and optimized with its simple model. It makes the PA have gain expansion and phase lag with the power, which allows the PA to have less amplitude-to-amplitude (AM–AM) and amplitude-to-phase (AM–PM) distortions. In addition, it improves the return losses of the PA by making the impedances for power matching and conjugate matching located closely. The implemented PA achieves the peak power-added efficiency (PAE) of 38.2% and the saturated output power ( $P_{\mathrm {sat}}$ ) of 17.1 dBm at 31 GHz while occupying the chip area of 0.16 mm2. It is also shown that the OP1 dB is improved by 1.7 dB, and the AM–PM distortion is reduced to only 1.1° due to the linearization technique. It is tested with 64-quadrature amplitude modulation (QAM) signals, which has a 400-MHz channel bandwidth (BW) and a 9.7-dB peak-to-average power ratio (PAPR). It achieves average output powers of 9.6/7.7 dBm with error vector magnitudes (EVMs) of −25/−30 dB for 64-QAM OFDM signals, efficiencies of 17.7%/12%, and the adjacent channel leakage ratio (ACLR) of −28.2/−32.8 dBc, respectively.

On-chip erbium-doped lithium niobate waveguide amplifiers

Abstract: Lithium niobate on insulator (LNOI), as an emerging and promising optical integration platform, faces shortages of on-chip active devices including lasers and amplifiers. Here, we report the fabrication on-chip erbium-doped LNOI waveguide amplifiers based on electron beam lithography and inductively coupled plasma reactive ion etching. A net internal gain of ~30 dB/cm in communication band was achieved in the fabricated waveguide amplifiers under the pump of a 974-nm continuous laser. This work develops new active devices on LNOI and will promote the development of LNOI integrated photonics.

A 27–46-GHz Low-Noise Amplifier With Dual-Resonant Input Matching and a Transformer-Based Broadband Output Network

Abstract: This letter presents a 27–46-GHz low-noise amplifier (LNA) in a 45-nm CMOS silicon-on-insulator (SOI) process. Two circuit techniques are employed to enhance the LNA bandwidth. First, the intrinsic gate-to-drain parasitic capacitance of the input transistor and the frequency-dependent behavior of the first-stage load impedance are explored to realize dual resonances for $S_{11}$ , thus extending the input matching bandwidth. Second, a network synthesis methodology is presented to convert a canonical second-order bandpass filter to a transformer-based output network, which realizes broadband power gain while occupying only one inductor footprint. In the measurements, the LNA 3-dB gain bandwidth is from 25.5 to 50 GHz with a peak gain of 21.2 dB at 37.8 GHz. The effective bandwidth of the LNA is limited by the 10-dB return loss bandwidth, which is from 27 to 46 GHz. The minimum noise figure (NF) is 2.4 dB at 27.8 GHz, and the NF remains <4.2 dB within the effective bandwidth. The measured IIP3 is −11.0 dBm at 38 GHz with 25.5-mW dc power consumption.