Performance Of Power Amplifier Research Articles

PAPR reduction of OTFS using an automatic amplitude reduction neural network with vendermonde matrix-based PTS and SLM algorithms

Orthogonal time frequency selectivity is considered one of the most promising advanced waveforms for high-mobility conditions in beyond-fifth-generation networks. A high peak-to-average power ratio in orthogonal time frequency introduces nonlinearity and degrades the power amplifier performance. In this work, we propose a novel automatic amplitude reduction neural network algorithm combined with partial transmission sequence and selective mapping methods using the Vendermonde matrix for generating phase sequences. In a conventional selective mapping methods or partial transmission sequence, selecting an optimal phase increases the complexity, which is overcome via Vendermonde matrix in a proposed framework. The minimization of the peak-to-average power ratio is obtained at the double-stage process: in the first stage, the threshold amplitude is set, and the amplitude exceeding the threshold is reduced by using an automatic amplitude reduction neural network and then the partial transmission scheme or selective mapping methods. The simulation results reveal that, compared with the conventional algorithms, the proposed algorithms yield a significant peak average-to-power ratio, bit error rate, and power spectrum density performance.

A High Gain, Low Power Operational Transconductance Amplifier Capable of Recording and Processing ECG Signals

Based on high output resistor current mirrors and differential pair inputs, a new operational transconductance amplifier (OTA) is designed in this paper that can collect, filter, denoise and amplify electrocardiogram (ECG) signals. The OTA is designed on a 0.18μm CMOS process with a supply voltage of 1.8V. In this experiment, the ECG signal generated by the human model is first simulated, which has a noise of 50 Hz from electromagnetic interference, especially the electrical power lines. The differential input pair is then connected to the model, and it is proved that it can denoise the common-mode noise. Finally, the designed OTA is connected to the manikin, and the experimental results are compared with the traditional OTA. The design achieves a differential-mode gain of 43.56dB and a common-mode gain of -31.36dB while maintaining a differential input voltage swing of 1Vpp. Experimental results show that the OTA can denoise and amplify the ECG signal without distortion.

Current controllers for optimizing laser cooling on cold atom experiments.

The design of a single chip current source based on a common power operational amplifier is presented and demonstrated for the purpose of controlling applied magnetic fields using bias/shim electromagnets in cold atom experiments. The efficacy of the design is realized via application to red-detuned polarization-gradient cooling of 87Rb down to 3 μK. Furthermore, we demonstrate Raman spectroscopy using these devices to apply current and so generate a precise, accurate, and reproducible magnetic field. This work is intended as a short tutorial for new graduate students and postdocs of laser cooling and trapping.

Design and fabrication of S-band power amplifier for wireless sensor networks

This paper discusses the process of designing and manufacturing a wideband power amplifier operating in the S-band. To amplify a low power and broadband radio frequency signals from 2.1 GHz to 2.5 GHz, the proposed power amplifier uses a diagram of a two-stages amplification with peak offset amplification frequency 2.3 GHz. The power amplifier is designed with a center frequency difference of 2.2 GHz and 2.4 GHz respectively to achieve a bandwidth of 400 MHz. The proposed power amplifier (PA) uses RF transistor SHF-0589 using gallium arsenide heterostructure field-effect transistor (GaAs HFET) technology for high gain and low power consumption. The complete amplifier achieves power gain 21.1 dB inband 2.1-2.5 GHz and achieve maximum power gain of 22.5 dB at the frequency of 2.4 GHz; the output power rise up to 33 dBm; input reflection coefficient (S11) reaches -19.2 dB and output reflection coefficient reaches -17.2 dB. The designed amplifier circuit can be used for wireless sensor networks operating at S-band.

Design of a Compact 2-6 GHz High-Efficiency and High-Gain GaN Power Amplifier.

In this paper, a novel wideband power amplifier (PA) operating in the 2-6 GHz frequency range is presented. The proposed PA design utilizes a combination technique consisting of a distributed equalization technique, multiplexing the power supply network and matching network technique, an LR dissipative structure, and an RC stability network technique to achieve significant bandwidth while maintaining superior gain flatness, high efficiency, high gain, and compact size. For verification, a three-stage PA using the combination technique is designed and implemented in a 0.25 μm GaN high-electron-mobility transistor (HEMT) process. The fabricated prototype demonstrates a saturated output power of 4 W, a power gain of 21 dB, a gain flatness of ±0.6 dB, a power-added efficiency of 39-46%, and a fractional bandwidth of 100% under the operating conditions of drain voltage 28 V (continuous wave) and gate voltage -2.6 V. Moreover, the chip occupies a compact size of only 2.51 mm × 1.97 mm.

Enhancing the power amplifier performance of an optical-OTFS modulation for optical communication system

Abstract Future wireless networks extensively employ the two-dimensional Optical-Orthogonal Time Frequency Space (O-OTFS) modulation system due to its increased dependability, flexibility, and data throughput. When there is a lot of movement, OTFS offers improved connectivity performance. While OFDM functions in the time-frequency domain, O-OTFS modulation acts in the delay-Doppler domain. This study provides an overview of how OTFS functions in the delay-Doppler domain, as well as its benefits and drawbacks. Next-generation networks utilize this modulation method in various applications, such as vehicle-to-vehicle communication, communication in mountainous areas, high-speed mobility, and train communication. This paper provides an easy-to-understand overview of the PAPR algorithms and its reduction in O-OTFS modulation.

Improving a $Ka$-Band Integrated Balanced Power Amplifier Performance by Compensating Quadrature Hybrid Mismatch Effects

Improving a $Ka$-Band Integrated Balanced Power Amplifier Performance by Compensating Quadrature Hybrid Mismatch Effects

A multi-objective optimization based doherty power amplifier and its matching network optimization method.

In the actual design process of traditional power amplifiers, there is a problem of being cumbersome and unable to simultaneously meet low power and saturation modes. Therefore, an improved multi-objective optimization algorithm proposed by decomposition is introduced to optimize its matching network to achieve overall optimization design of power amplifiers. The algorithm, matching network, and optimized power amplifier performance are simulated and verified. The experimental outcomes denote that on the logic function with Zener diode transistor, the proposed algorithm has a mean generation distance index of 5.03E-3, which is lower than most algorithms. Its overall comprehensive performance is better than the comparison algorithm, and compared to the comparison algorithm, it converges more quickly in the early stage of iteration on 1 and 2, and tends to stabilize in the 40th generation, and completes convergence in the 80th generation. In addition, the optimal solution has already begun to appear around the 25th generation and reached saturation around the 70th generation. At the same time, in the actual working bandwidth, the optimized power amplifier saturation efficiency reaches 51.5%~61.9%, and the efficiency at 6dB power backoff is about 44.4%~56.5%. Overall, the algorithm proposed in the study is effective in optimizing power amplifiers and their matching networks, effectively solving the problem of insufficient efficiency in low power modes in traditional designs.

Development of linear power operational amplifier power supply with pre-regulated voltage controller for TPS correction magnets

The Taiwan Photon Source (TPS) is a renowned 3 GeV synchrotron accelerator light source. Over the past decade of successful operation, it has demonstrated outstanding performance, notably in average beam trip downtime, meeting international standards. A continuous regimen of scheduled equipment upgrades has been maintained across all subsystems to ensure ongoing improvement and the preservation of an optimal research facility environment. The central focus of this study revolves around the design and realization of a TPS correction magnet power supply employing Linear Power Operational Amplifiers (LPOA) in conjunction with a pre-regulated voltage controller. The power source predominantly features APEX Corporation's PA05 LPOA, characterized by bipolar output, high internal power dissipation, and wide bandwidth. Additionally, a DC Current Transducer (DCCT) was employed as the current feedback element, integrated with the pre-regulator voltage controller to form a closed-loop current modulation circuit, providing the variable voltage required by the LPOA. Through these measures, we have successfully developed an LPOA power supply unit equipped with a pre-regulated voltage controller for TPS correction magnets. The prototype device boasts a maximum output current of ±10 A, operating at 24 V. Validation through control loop design has led to rapid and stable output current performance. The output current ripple is maintained within 100 μA, with a rise time of 75 μs during step response. During frequency response testing utilizing a 0.1 V disturbance signal, the gain margin resides within -3 dB at an 11.2 kHz bandwidth and the phase margin within -45∘ at a 5.1 kHz range. Long-term output current stability is sustained within ten ppm. Finally, a hardware prototype circuit has been constructed in the power supply laboratory, featuring a ±24 V input voltage and ±10 A output current, achieving a maximum rated power of 240 W.

Comparative Analysis of SS, SP, PP and PS Topologies for Magnetic Coupled Wireless Power Transfer System Composed of the Negative Resistor

In recent years, the concept of the negative resistor (NR) has been proposed and applied in the magnetic coupled wireless power transfer (MC-WPT) system to improve the stability of power transfer. However, it remains a fundamental challenge to find the characteristic differences and applications of the four basic NR-based MC-WPT topologies. In this paper, the circuit models of the four basic NR-based MC-WPT topologies: series-series (SS), series-parallel (SP), parallel-parallel (PP), and parallel-series (PS) are established, and their characteristics are analyzed and compared by using circuit theory, which enables engineers to determine and select topologies to suit different applications and requirements. Theoretical analysis shows that the compensation methods of the transmitter and receiver of the NR-based MC-WPT system would affect the operating frequency and output characteristics of the system. Moreover, by comparative analysis, the conditions and applicable ranges for a stable output of different topologies were provided. Finally, the experimental prototypes are set up by using the power electronic inverter and operational amplifier, and the voltage gain ratios of the four basic NR-based WPT topologies under the variations of transfer distance and load are observed. The experimental results validate the correctness of the theoretical analysis.

Methods of reducing antenna bandwidth requirements for envelope elimination and restoration transmitter

The task of radio transmitting path efficiency increasing is relevant both for stationary high-power applications and for autonomous low-power devices. The highest efficiency can be achieved in switching operating modes (classes D, E, F). For the amplification of modern spectrally efficient broadcast and telecommunication signals with variable amplitude, for example, with OFDM, the use of switching operating modes is possible only with the use of "synthetic" amplification methods. The most promising for application can be considered Envelope Elimination and Restoration (EER) method, which is successfully used in the field of high-power broadcasting in the LF, MF and HF bands, and is the object of a large number of studies aimed at expanding its scope. Transmitting devices of radio communication and broadcasting systems in some cases are forced to work with an electrically short antenna. However, when operating with OFDM signals to a narrow-band load, high-efficiency EER transmitters require matching with an antenna circuit with an SWR of at least 1.05 in the signal frequency band. Thus, the task of antenna bandwidth requirements reducing for EER transmitter is relevant. To solve it, a simulation model was previously developed and verified to study the operation of EER switching RF power amplifiers for a narrow-band load. With its help, the dependence of output signal distortion level on the envelope path LPF parameters was studied. This article proposes and analyzes hardware circuit solutions aimed at reducing the transmitter sensitivity to antenna bandwidth. The analysis of hardware methods for reducing the EER transmitter sensitivity to the resonant antenna SWR (passband) showed the following: 1. The damping circuit, together with a double-sided loaded envelope path LPF, allows you to reduce antenna SWR requirements to a maximum value of 1.22, while the allowable antenna bandwidth can be reduced to five signal bands. 2. The high-pass filter diplexer proposed in this paper, together with a double-sided loaded envelope path LPF, makes it possible to reduce antenna SWR requirements to a maximum value of 1.47, and the allowable antenna bandwidth can be reduced to 2.5 signal bands. The disadvantages of this method include the need, depending on the antenna used, for individual design and manufacture of high-pass filter diplexers installed in the low-frequency path of each amplifying cell of the transmitter. To expand the range of antennas used, it is possible to switch capacitors of the high-pass filter diplexer from a set of 2 ... 3 pieces. Data on the production of transmitters with the proposed HPF diplexer has not been found to date. 3. Multi-phase PWM when using a 2nd order unilaterally loaded low-pass filter and installing 2nd harmonic rejectors of the operating frequency in the cells of the RF path allows you to work on antennas with a bandwidth of up to half the signal bandwidth. Restrictions on the antenna bandwidth and its SWR are imposed only by the uneven antenna frequency response in the transmitted signal band. The disadvantages of this method include the need to install narrow-band rejectors that block the power supply circuit of each RF cell in terms of the 2nd harmonic, which makes such a transmitter a custom product for a fixed operating frequency. 4. The most promising solution should be considered the use of a high-pass filter diplexer, which allows relatively simple means to expand the permissible SWR of a narrow-band antenna in the signal band from the initial value of 1.05 to 1.47.

A Thorough Evaluation of GaN HEMT Degradation under Realistic Power Amplifier Operation

In this paper, we experimentally investigate the effects of degradation observed on 0.15-µm GaN HEMT devices when operating under realistic power amplifier conditions. The latter will be applied to the devices under test (DUT) by exploiting a low-frequency load-pull characterization technique that provides information consistent with RF operation, with the advantage of revealing electrical quantities not directly detectable at high frequency. Quantities such as the resistive gate current, play a fundamental role in the analysis of technology reliability. The experiments will be carried out on DUTs of the same periphery considering two different power amplifier operations: a saturated class-AB condition, that emphasizes the degradation effects produced by high temperatures due to power dissipation, and a class-E condition, that enhances the effects of high electric fields. The experiments will be carried out at 30 °C and 100 °C, and the results will be compared to evaluate how a specific RF condition can impact on the device degradation. Such a kind of comparison, to the authors’ knowledge, has never been carried out and represents the main novelty of the present study.

High Bandwidth Active Gate Driver for Simultaneous Reduction of Switching Surge and Switching Loss of SiC-MOSFET

This study investigates an active gate driver (AGD) for an SiC-MOSFET. The source current feedback type AGD utilizes the induced voltage of the source wire inductance as a negative feedback signal to regulate the source current di/dt. Recent improvements in the switching performance of the AGD is limited due to the feedback system bandwidth. In this paper, a high bandwidth current feedback type power operational amplifier is applied as the gate drive circuit. Switching characteristics of the conventional resistive gate driver and AGD are experimentally investigated via a double pulse test setup. The switching setup condition is 700 V / 80 A. This paper describes the development of the AGD circuit and experimental results. The over-shoot and ringing of the Vds and Is are reduced using the AGD. Moreover, the switching loss is simultaneously reduced.

A Lightweight and Robust Drone MHz WPT System via Novel Coil Design and Impedance Matching

This paper proposes a comprehensive approach to address the challenges posed by the simultaneously varying dc load and coil coupling in drone wireless charging, which inevitably occur during battery charging and landing positioning. The combination of two new coil designs, a quasi-elliptic transmitting (Tx) coil and a “belt” receiving (Rx) coil, enables adequate power transfer at megahertz (e.g., 6.78 MHz) and over a large circular landing area. The on-board “belt” Rx coil (5.8 g) especially helps achieve lightweight and minimize air resistance. A load-pull-based impedance analysis is then performed to clarify the need for an impedance matching network (IMN) on both Rx and Tx sides (i.e., Rx-IMN and Tx-IMN). A new Rx-IMN explicit design is specially developed to significantly limit the range of variation in the coupling coil input impedance, thereby helping to simplify the design of the Tx-IMN to ensure an efficient power amplifier operation. With the proposed coil and IMN designs, actual drone wireless charging experiments demonstrated improved system dc-dc efficiency (max. 83.5%) and dc-dc voltage ratio stability at three representative landing positions (i.e., minimum, medium, and maximum coil coupling).

Design Optimization of Ultra Low Power Operational Transconductance Amplifier With Nano TFETS Using Push–Pull Structure For Bias Current Optimization

Design Optimization of Ultra Low Power Operational Transconductance Amplifier With Nano TFETS Using Push–Pull Structure For Bias Current Optimization

High Linear and Temperature Insensitive GaAs Power Amplifier Operating at 3.3–3.6 GHz Using a Multi-Feedback Branch Bias Circuit

This letter describes a design of a 3.3–3.6-GHz GaAs heterojunction bipolar transistor (HBT) power amplifier (PA) with high linearity and temperature insensitivity for the fifth-generation (5G) of new radios (NRs). By involving a multi-feedback branches bias circuit, the voltage at the feedback node of the bias circuit can achieve dynamic self-tuning to stabilize the base voltage as the amplifier’s input power grows and stabilize the bias current as the temperature increases as well. A three-stage common source structure PA in the form of a monolithic microwave integrated circuit (MMIC) is designed using a multi-feedback branch bias circuit with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.5\times1.2$ </tex-math></inline-formula> mm. Measured with continuous wave (CW) signals, the output 1-dB compression point at 3.3–3.6 GHz is 34 dBm. The linearity of the PA is also evaluated using a 5G-NR 100-MHz 64-quadratic-amplitude modulated (QAM)-orthogonal frequency division multiplexing (OFDM) signal with a 7-dB peak-to-average-power ratio (PAPR). The proposed PA achieves an adjacent channel power ratio (ACPR) less than −49.5 dBc at an average power of 28 dBm with a power-added efficiency (PAE) of 20% without the use of digital pre-distortion (DPD). In the temperature range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 40\,\,^{\circ }\text{C}$ </tex-math></inline-formula> to 120 °C, the variance of bias current, small signal gain, PAE, output power at 1-dB compression point (OP1dB), and ACPR is relatively minor. This design is ideally suited for 5G communication systems due to its high linearity and temperature insensitivity.

A 40% PAE and 34dBm Peak OIP3 CMOS Power Amplifier with Integrated Zero Power Consumption Phase Linearizer

In this paper, an Integrated Phase Linearizer (IPL) technique is designed to improve the linearity performance of a CMOS power amplifier (PA). The IPL is integrated at the gate of the PA so that the effect of the parasitic gate-to-source ([Formula: see text]) capacitance of the main transistor is compensated by the linearizer. Thus, it improves the 3rd-order intermodulation point (OIP3) without trading-off the power added efficiency (PAE). The proposed solution is designed and fabricated in an 180[Formula: see text]nm CMOS technology process consuming the chip area of 2.25[Formula: see text]mm2. At the operating frequency of 2.45[Formula: see text]GHz, it exhibits a gain of 11.14[Formula: see text]dB with unconditional stability characteristics from 1[Formula: see text]GHz to 10[Formula: see text]GHz. Biased quiescent current of 19.35[Formula: see text]mA, the IPL-PA delivers a maximum output power of 15.20[Formula: see text]dBm with 40.86% peak PAE, 34.91[Formula: see text]dBm of peak OIP3 and maximum power consumption of 63.65[Formula: see text]mW at 2.45[Formula: see text]GHz with supply voltage headroom of 1.8[Formula: see text]V. The proposed linearization scheme proved to be an excellent solution for low-power transceivers integration.

A large-signal scaling model of high-power GaN microwave device

With the rapid development of wireless communications, GaN HEMT, which has various advantages of high power density, high electron mobility, and high breakdown threshold, receiving increasing attention. Microwave power amplifiers based on GaN HEMTs are widely used in many fields, such as communication, medical, and detection instruments. In the accurate design of GaN microwave power amplifiers, reliable RF large signal model is vitally important. In this paper, a scalable large-signal model based on EEHEMT model is proposed to describe the properties of multifinger AlGaN/GaN high electron mobility transistor (HEMT) accurately. A series of scaling rules is established for the intrinsic parameters of the device, including drain-source current &lt;i&gt;I&lt;/i&gt;&lt;sub&gt;ds&lt;/sub&gt;, input capacitance &lt;i&gt;C&lt;/i&gt;&lt;sub&gt;gs&lt;/sub&gt; and &lt;i&gt;C&lt;/i&gt;&lt;sub&gt;gd&lt;/sub&gt;, which take into account both the gate width of a single finger and the number of gate fingers. With the proposed scalable large-signal model, the performance of the L-band GaN high-efficiency power amplifier with a gate length of 14.4 mm is analyzed. This amplifier demonstrates outstanding performance, with the output power reaching to 46.5 dBm and the drain efficiency arriving at over 70% of the frequency range from 1120 MHz to 1340 MHz. Good agreement between the simulations and experiments is achieved, demonstrating the excellent accuracy of the proposed model. Moreover, the proposed model can further predict the performance of high-order harmonics, providing an effective tool for designing advanced high-power and high-efficiency microwave power amplifiers. Certainly, the EEHEMT model fails to characterize the dynamical behavior induced by trapping and self-heating effects. Thus, for further consideration, scaling models for the thermal resistance and heat capacity need further investigating to broaden the application scope of the proposed model in the case of continuous waves.

An ultrahigh performance laser driver based on novel composite topology enhanced Howland current Source.

Laser diodes (LDs) are used in a wide range of applications, such as optical wireless communications and LIDAR. To meet the demanding requirements of LDs for high accuracy and stability of the injection current, a high-precision, high stability LD driver with overvoltage protection is proposed. A novel structure based on enhanced Howland current source is described: composite topology enhanced Howland current source (CTEHCS), which has the advantages of high precision, high stability, and extensive regulation range. A 20-bit DAC and high-precision reference source are used to form a front-stage DAC circuit for precise and stable voltage reference. A closed-loop feedback calibration loop is applied to eliminate significantly the absolute errors and auxiliary calibrating of the effect of power operational amplifier on the temperature rise of critical devices. An innovative overvoltage protection circuit is designed for the load side of the CTEHCS, and the protection range can be flexibly set to 4/5/6V to avoid damage to loads such as LDs. The noise performance, accuracy and stability, modulation bandwidth, nonlinear error, overvoltage protection performance, and turn-on and turn-off time of the experimental prototype are described in detail.

Implementation of class‐E/F3 power amplifiers based on the variations of the MOSFET grading coefficient, built‐in potential and output capacitance along with their roles in MOSFET selectivity

SummaryIn this paper, a theoretical analysis of the class‐E/F3 power amplifier based on the variation of the grading coefficient m1 and its vital role in MOSFET selectivity to operate safely under given design specifications is presented while the nonlinearity of the drain‐to‐source capacitance is considered. Moreover, the importance of Vbi and Cjo in designing the class‐E/F3 amplifier is investigated. To clarify how the grading coefficient m1 and the other mentioned parameters can directly influence the power amplifier performance and also its elements, these MOSFET parameters are considered as the independent variables of the calculated equations and consequently define the horizontal axis of the obtained plots. Accordingly, as the grading coefficient increases, the maximum switch voltage increases and values of the output power and output power capability decline. Moreover, to prove the reliability of the carried‐out analysis in selecting proper MOSFETs, the performances of three amplifier samples utilizing IRF510, IRFZ24N, and 2SK2504 MOSFETs with different grading coefficient m1 and almost similar Vbi and Cjo are studied. Then, by comparing the results of amplifiers with three MOSFETs, IRF510, IRF530, and IRF540, with similar grading coefficient and different values of Vbi and Cjo, the significance of considering the values of Vbi and Cjo is investigated. Eventually, three amplifiers with 2SK2504, IRF510, and IRF530 MOSFETs have been simulated, implemented, and tested and measurement results agreed well with the theoretical and simulation results.