Linear Amplifier Research Articles

EFFICIENCY ANALYSIS OF SWITCHING CONVERTER-MODULATOR

The article discusses methods of highly efficient linear RF power amplifier and transmitter design for future 5G/6G networks. Based on a consideration of various known methods for constructing high-efficiency power amplifiers, the prospects of developments using the envelope elimination and restoration (EER, or Kahn method) and envelope tracking (ET) method are substantiated. The prospects for implementing PWM switching converter-modulator for these methods are assessed. Based on the evaluation calculations performed, it is shown that this structure can potentially be used as an EEP/ET modulator for a number of 5G/6G applications and will have advantages over structures using class AB amplification.

Augmented Phase-Normalized Recurrent Neural Network for RF Power Amplifier Linearization

Augmented Phase-Normalized Recurrent Neural Network for RF Power Amplifier Linearization

Implementation of Alternating Direction Method of Multipliers for Solving Power Amplifier Linearization Problem: Theoretical Foundations and Proof of Concept

Implementation of Alternating Direction Method of Multipliers for Solving Power Amplifier Linearization Problem: Theoretical Foundations and Proof of Concept

Dynamic Range of a Digital Radio Receiver with a Photonic Analog-to-Digital Converter

The article is devoted to determining the requirements for the preliminary, analog part of the receiver and its structure when using a photonic ADC. The subject of research in this case is the issues of ensuring a large dynamic range of signals at the input of a receiver with a photonic ADC. The parameters and properties of the PADC with optical quantization and discretization are investigated. The distinctive features of the PADC are a high sampling rate, about 100 GHz, the possibility of increasing the carrier-to-noise ratio (CNR) and the effective number of bits (ENOB) due to the amplification of the carrier or modulating signal, and a low noise factor of microwave photonic elements. The presented advantages make it possible to reduce the structure of the analog part of the receiver by eliminating the mixer and anti-aliasing filter, as well as to achieve better sensitivity due to a lower level of internal noise. The study also revealed a limitation of the dynamic range imposed by the photonic element base. The reason for the limitation is the nonlinearity of the electro-optical modulators used and the limitation of the upper limit of the dynamic range to the photodetectors used. All this leads to requirements under which the analog part must provide significant amplification of the received radio signal, as well as the implementation of a variable gain. As a result, structural solutions are presented in the form of multichannel switching circuits. The principle of operation lies in the fact that each channel, consisting of a cascade of linear amplifiers and a PADC, has a different gain, and in the digital processing unit, channels are compared and switched depending on the signal level. At the same time, the level should be in the 'corridor' of acceptable values for the application of the PADC and within the dynamic range. The presented structural solutions will make it possible to implement radio receivers capable of receiving and processing a microwave signal without transferring the signal to an intermediate frequency. At the same time, the required signal amplification level of 105 - 106 can be achieved, which makes it possible to achieve a signal level of 2.5-9.5 V, at which the photonic analog-to-digital converter has the best CNR and ENOB indicators.

A nano-positioning system based on an optimal two-stage linear displacement amplifier

Nano-positioning systems with large motion ranges often employ displacement amplifiers with poor linearity and a large footprint. Here, we propose a compact nano-positioning system comprising an optimally designed two-stage displacement amplifier with linear input-output relationship over a large motion range. The first stage is a truncated bridge amplifier whose size is 25% of a conventional bridge amplifier, while the second stage is a modified lever-type displacement amplifier whose amplified motion direction can be chosen as desired. It is proposed to exploit the compliance of the structure to improve its linearity by operating the truncated bridge amplifier at a specific optimal angle. A simple reduced-order model is proposed and is shown to agree with finite element analysis to within 1%. Further, the variation in the amplification ratio at various payloads are analysed as function of input displacement. Subsequently, a two-stage amplifier with amplification 28 demonstrating a linear range of 940 µm is fabricated using acrylic. This amplifier’s nonlinearity is less than 5.2%, representing about 10-fold improvement compared to a conventional bridge amplifier. Lastly, a nano-positioner employing an optimal amplifier is fabricated using spring steel and demonstrated to possess nonlinearity less than 1.5% over a range of 360 µm and a natural frequency of 210 Hz with a footprint of 21 cm2, which represents a substantial improvement in range-to-footprint ratio compared to other amplifiers of similar natural frequencies.

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.

Single-phase binary phase-shift keying, quadrature phase shift keying demodulators using an XOR gate as a phase detector

A single-phase/single-loop multiple-phase-shift-keying (<em><span lang="EN-US">m</span></em><span lang="EN-US">-PSK)</span><span lang="EN-US"> demodulator is described. The demodulator relies on a linear range of an exclusive-OR (XOR) gate employed as a phase detector. The phase controller takes the average output from the XOR gate and performs a sub-ranging/re-scaling operation to provide an input signal to a voltage-controlled oscillator (VCO). The demodulator is truly modular which theoretically can be extended for an </span><em><span lang="EN-US">m</span></em><span lang="EN-US">-PSK signal. The proposed single-phase binary-/quadrature-PSK (BPSK/QPSK) demodulators have been implemented with low-cost discrete components. The core of the phase controller simply relies on number of stages of a full-wave rectifier and a linear amplifier built from well-known op-amp-based negative feedback circuits. The demodulator prototypes operate from a single supply of 5 V. At a carrier frequency of 100 kHz, both the BPSK and QPSK demodulators achieved the maximum symbol rate of 20 ksymbol/s respectively. At these symbol rates, the BPSK and QPSK demodulators deliver symbol-error rates less than 2×10<sup>-10 </sup>and 7×10<sup>-10</sup>.</span>

Minimizing Training Signal Length for Power Amplifier Characterization and Linearization

Minimizing Training Signal Length for Power Amplifier Characterization and Linearization

Improved Linearity and Efficiency of 5-GHz HBT Power Amplifier Using Transformer-Based Second Harmonic Trap Network

Improved Linearity and Efficiency of 5-GHz HBT Power Amplifier Using Transformer-Based Second Harmonic Trap Network

Modified modeling and internal model control method of thrust ripples in PMLSMs for ultraprecision air-bearing linear feed systems

With the aim of attenuating thrust ripples in ultraprecision air-bearing linear feed systems, a simple and effective internal model control (IMC) system is herein presented based on a modified modeling and identification method of permanent magnet linear synchronous motors (PMLSMs). First, flux linkage equations were used to describe the volt–ampere characteristics of PMLSMs and provide a thrust expression in a differential form based on the principle of virtual work. Then, an analytical formula was obtained through derivation based on the condition of field-oriented control. On this basis, an IMC compensator was designed using an inverse model to attenuate nonlinear thrust effects, and an extended Kalman filter (EKF) was adopted to estimate the actual current in an analog linear amplifier. The boundedness of the nonlinear system was analyzed based on the convergence condition; furthermore, the stability of the proposed IMC compensator with EKF could be guaranteed. Then, an accurate model and thrust parameters were obtained using an identification experiment on an air-bearing linear platform driven by a linear analog amplifier. To demonstrate the coupling effect of current on thrust and confirm the effectiveness of the proposed method, both simulations and experiments were performed at a uniform velocity under extra loads of different weights; then, an extended state observer (ESO) was introduced as a comparative method. Finally, the results of the following error indicated that the proposed method demonstrated improved performance in terms of overcoming the influence of nonlinearity and that it results in smooth velocities in steady states.

Four-state continuous-variable quantum key distribution with a hybrid linear amplifier

Four-state continuous-variable quantum key distribution with a hybrid linear amplifier

Highly sensitive hybrid optical receiver with a compact 1.4 GHz linear transimpedance amplifier in 55 nm CMOS

Highly sensitive hybrid optical receiver with a compact 1.4 GHz linear transimpedance amplifier in 55 nm CMOS

Third-Order Intermodulations Phase Shifting in Power Amplifiers for Spatial Filtering in Multi-Beam 5G mmW Phased Array

This paper proposes an innovative concept of spatial third-order intermodulation products (IMD3) filtering in millimeter-wave 5G phased arrays. This technique aims to relax the linearity constraints on the power amplifiers (PA) and thus power consumption. Implementation of independent control of the phase of IMD3 is proposed by using the nonlinear output capacitance of metal-oxide semi-conductors (MOS) amplifiers under phase-controlled second harmonic injection. The implemented control uses beamforming properties to perform spatial filtering of IMD3 product. A second harmonic injection on a power amplifier is proposed in STMicroelectronics CMOS065SOIMMW technology at 28 GHz. It shows phase control of IMD3 with a range of 35 degrees, allowing relaxation up to 17 dB on the linearity of large phased array power amplifiers.

Adversarial Modeling Regularization for Modeling and Linearization of Power Amplifiers

Overfitting problem is very common in the coefficient identification process of digital predistortion (DPD) technique. Especially in some related DPD topics, the overfitting problem seriously limits the linearization performance. In this article, to improve the robustness of coefficient identification, we present the adversarial modeling regularization (AMR) technique. By regarding the linear-in-coefficient power amplifier (PA) behavioral models as the prior knowledge of the PA itself, the proposed regularization constrains the PA model’s coefficients by evaluating the fitting performance of other adversarial models. In addition, we present two complexity reduction strategies for the AMR. The AMR is extended and validated under four related tasks that are prone to overfitting: the few-sample learning, the piecewise DPD technique, the aliasing-sampling technique, and the band-limited technique. The experiment results show that the proposed technique can dramatically improve the forward behavioral modeling and linearization performance compared with the other state-of-the-art algorithms in all tasks.

Phase-Normalized Neural Network for Linearization of RF Power Amplifiers

Phase-Normalized Neural Network for Linearization of RF Power Amplifiers

Hydraulic simulation of an urban river affected by treated effluent based on signal processing theory and physically based models

Study regionThe Tonghui River–a treated effluent-affected urban river located in Beijing, China. Study focusInspired by the signal processing theory, this study presented a simulation scheme for the treated effluent-affected river based on hydrologic monitoring, pattern recognization, pattern extraction, and hydrologic/hydraulic modelling. It aimed to precisely depict the river flow patterns when detailed wastewater treatment plant effluent data was absent and to fill in the gap of the application of signal-based hydrological time series processing methods in physically based hydraulic simulation. New hydrological insights for the regionDiurnal and semidiurnal patterns caused by the wastewater treatment plant (WWTP) effluent were recognized from the water level series using the continuous wavelet transform. Due to their small amplitudes, they were masked during flood events but dominated the flow regime in dry seasons. Based on the discrete wavelet decomposition and Fourier series fitting, these periodical patterns were extracted and fitted. With a preliminarily calibrated hydraulic model and a linear signal amplifier, a simulated WWTP effluent was retrieved. Dry seasons simulation utilizing the simulated effluent obtained significantly better performance than using the average effluent data from the aspects of conventional evaluation metrics, cross-wavelet transform, and wavelet coherence.

Long-distance continuous-variable quantum key distribution with feasible physical noiseless linear amplifiers

Long-distance continuous-variable quantum key distribution with feasible physical noiseless linear amplifiers

Improving the sensitivity of distributed phase estimation under noisy Gaussian environment with noiseless linear amplification

The deterioration of precision caused by quantum decoherence in dissipative environments is a longstanding problem in the development of distributed quantum metrology. Therefore, it is significant to effectively overcome the entanglement-distribution loss and channel noise of dissipative environments and improve the measurement-sensitivity. Here, we introduce noiseless linear amplifier (NLA) based on photon catalysis into distributed phase estimation to mitigate the loss and noise. Through utilizing a series of reduction and equivalence relations to simplify the problem of distributed phase estimation to a single-parameter estimation situation, our results show that Photon catalysis (PC)-NLAs can effectively mitigate the loss and noise of dissipative environments, and greatly improve the measurement-sensitivity. More interestingly, we find that adding thermal photons of environment has positive contributions on the measurement-sensitivity under certain circumstances. Our scheme should prove valuable for the global wide-area quantum sensor network.

Attention mechanism based bidirectional LSTM model for broadband power amplifier linearization

AbstractIn this letter, a novel digital predistortion (DPD) model for broadband power amplifier (PA) linearization is proposed, namely Attention Mechanism based Bidirectional Long Short‐term Memory Network (AM‐BiLSTM) model. In order to verify the linearization performance of the AM‐BiLSTM model in digital predistortion process, a 100 MHz bandwidth 5G new radio (5G NR) signal is employed to test a sub‐6G PA operating at 2.6‐GHz. The experimental results show that the adjacent channel power ratio (ACPR) of the PA with AM‐BiLSTM model can be improved by 24 dB which is 6 dB and 3 dB better than the generalized memory polynomial (GMP) model and the Chebyshev polynomials LSTM (CP‐LSTM) model in ref [1], repspectively. Therefore, the proposed AM‐BiLSTM model is very effective for the DPD linearization of broadband PAs.

Discontinuous Speed Control of PMDC Motors with Chattering Attenuation

In most applications, electric drives are actuated using on/off devices due to their low cost and also due to the relatively high power consumption of the electric drives which make applying linear power amplifiers very costly. In this paper, the operation of PMDC motors under discontinuous control action is analyzed. In addition, to reduce chattering, boundary layer solution has been addressed. Both suggested control techniques have been applied to a PMDC motor model in a software simulation using MATLAB. The results show better performance of boundary layer technique due to the reduced chattering. Index Terms— PMDC Motor, Discontinuous Control, Boundary Layer.