One drawback of OFDM systems is the high peak-to-average power ratio, which imposes strong requirements on the linearity of power amplifiers (PAs). Such linearity requirements translate into high back-off that results in low power efficiency. In order to improve power efficiency, a PA nonlinearity cancellation (PANC) technique is introduced which reduces the nonlinear distortion effects on the ...

In this study, balanced and single ended class-E power amplifiers (PAs) were designed and realized for 3.5–3.8GHz band by using Gallium Nitride high electron mobility transistor (GaN HEMT). Realizations were made on low loss Rogers RT5880 dielectric material which has 0.254mm thickness and 2.2 dielectric constant. Proposed balanced class-E PA has approximately 20W (43 dBm) output power with 80%...

The energy efficiency of battery-operated portable applications can be improved by increasing the efficiency of power amplifiers (PAs). By dynamically changing the supply voltage from the fixed battery supply using a DC-DC converter, the PA can be operated with high efficiency during power back-off. This paper presents the system level requirements for a buck converter and other blocks in a dyn...

Many modern communication signal formats, such as orthogonal frequency-division multiplexing (OFDM) and code-division multiple access (CDMA), have high peak-to-average power ratios (PARs). A signal with a high PAR not only is vulnerable in the presence of nonlinear components such as power amplifiers (PAs), but also leads to low transmission power efficiency. Selected mapping (SLM) and clipping...

Static X-parameter (XP) models for RF power amplifiers (PAs), derived from both simulations and nonlinear vector network analyzer (NVNA) measurements, are investigated for the prediction of PA performance under dynamic signal conditions such as in envelope tracking (ET). The instantaneous AM-AM, AM-PM and PAE predictions of XP models extracted from simulation are compared under ET dynamic signa...

Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Mei Yen Cheong Name of the doctoral dissertation Development of digital predistorters for broadband power amplifiers in OFDM systems using the simplicial canonical piecewise linear function Publisher School of Electrical Engineering Unit Department of Signal Processing and Acoustics Series Aalto University publication series D...

A novel topology based on linear power amplifiers (PAs) and real-time sinusoidal voltage-adjustment supply systems (RTSPSs) for a permanent magnet synchronous motor (PMSM) drive system is proposed in this article. Here, PAs are applied to achieve high-precision control minimize the torque ripple harmonic loss caused by nonlinearities of inverter traditional space vector pulsewidth modulation. M...

Behavioral modeling technique provides an efficient and convenient way to analyze and predict the performance of the RF power amplifiers (PAs) in system-level, and thus helps to construct a suitable predistorter to linearize the PA system. To accurately describe the nonlinear dynamic characteristics of PAs, an orthonormal Hermite polynomial basis neural network (OHPBNN) is utilized to represent...

In this article, we present a novel recurrent neural network (RNN)-based behavioral model to linearize radio frequency (RF) power amplifiers (PAs) under wideband excitations. Based on the lightweight Just Another NETwork (JANET) unit, propose new structure that is especially suitable for modeling complex behavior of RF PAs. A signal preprocessing technique developed interaction between amplitud...

The thesis demonstrates the design of high frequency SiGe bipolar integrated power amplifiers (PAs) for mobile communication terminals with the support of electromagnetic (EM) simulation. Three single-ended PA designs for mobile terminals operating up to 6GHz have been designed , realized and measured. The realized amplifiers fulfill the assumed requirements in terms of overall performance main...