Broadband RF Power Amplifier Research Articles

Real-Time Optimization of Dynamic Predistortion Model for 5G Massive MIMO Broadband RF Power Amplifier

Real-Time Optimization of Dynamic Predistortion Model for 5G Massive MIMO Broadband RF Power Amplifier

Broadband RF Power Amplifier with Combination of Large Signal X-Parameter and Real Frequency Techniques

Broadband RF Power Amplifier with Combination of Large Signal X-Parameter and Real Frequency Techniques

Sampling Rate Reduction for Digital Predistortion of Broadband RF Power Amplifiers

In this article, we present a novel technique to build digital predistorters that can linearize broadband power amplifiers (PAs) using reduced sampling rates. In contrast to conventional digital predistortion (DPD) where oversampling is necessary to avoid aliasing effect, the proposed method cancels the aliasing distortion using a sliced multistage cancellation scheme. A large reduction of sampling rate can be achieved in digital implementation of DPD, significantly reducing power consumption and implementation cost. Experimental results show that a DPD with a sampling rate of merely 1.5×, instead of 5×, signal bandwidth, can still produce satisfactory performance within the linearization bandwidth but consume only one-third of power, compared with that using the conventional approaches. The proposed technique provides a promising solution for the next-generation 5G systems, where large signal bandwidths are required.

High-Power 20-100-MHz Linear and Efficient Power-Amplifier Design

This paper presents modeling and analysis of the realization of high-power broadband RF power amplifiers (PAs) and power combiners. In the scope of the study, a model is proposed for a transmission line with a ferrite core, which is the basic building block for the transmission line transformers (TLTs) used in broadband high-power amplifiers and power combiner/divider networks as a building block. Simulated performances of the designed networks using the proposed model possess high conformity with the empirical performance of the corresponding realized networks. Therefore, broadband TLT networks with low insertion loss, high power-handling capability, and low return loss are realized. RF power combiner/divider networks with wide frequency bandwidth and high isolation are also implemented. By using class-B biased pushpull network topology, a linear and wideband RF PA is realized with high drain efficiency at high output power levels. In order to broaden the operating frequency range of the indicated amplifier, a novel technique for TLT utilization that matches the output impedance of the RF power transistor in wideband is proposed and realized. Measurement results satisfy the design specifications.

Volterra series based predistortion for broadband RF poweramplifiers with memory effects

RF power amplifiers (PAs) are usually considered as memoryless devices in most existing predistortiontechniques. However, in broadband communication systems, such as WCDMA, the PA memory effects are significant, and memoryless predistortion cannot linearize the PAs effectively. After analyzing the PA memory effects, a novelpredistortion method based on the simplified Volterra series is proposed to linearize broadband RF PAs withmemory effects. The indirect learning architecture is adopted to design the predistortion scheme and the recursiveleast squares algorithm with forgetting factor is applied to identify the parameters of the predistorter. Simulationresults show that the proposed predistortion method can compensate the nonlinear distortion and memory effectsof broadband RF PAs effectively.

A pulsed, broadband NMR spectrometer

A pulsed nuclear magnetic resonance spectrometer suitable for measurements in solids is described. The spectrometer is phase coherent, and the pulse timing is synchronous with the operating frequency of the spectrometer. The apparatus uses a versatile pulse programmer and a gated broadband rf power amplifier which delivers 1.6 kW at 60 MHz with a 3-db bandwidth of 5 to 90 MHz. With the exception of the probe, the spectrometer does not contain any tuned elements. This permits short (0.5 μsec) recovery times between the end of the rf pulse and the start of the signal. The spectrometer relies heavily upon the use of commercially available modules. A detailed description of the spectrometer construction and a discussion of typical operating characteristics are presented.