Digital Predistortion of Wideband Signals with Reduced Complexity Based on Feedback Wiener System, Journal of Telecommunications and Information Technology, 2021, nr 2

Digital predistortion (DPD) using baseband signals is commonly used for power amplifier linearization. This paper is devoted to this subject and aims to reduce DPD complexity. In this study, we propose a structure that allows to decrease the number of DPD parameters by using multiple blocks, with each one of them dedicated to characterizing the non-linear behavior and/or memory effects. Such a structure is based on the feedback Wiener system, involving a FIR filter used as a feedback path to reproduce the PA inverse dynamics. A memory polynomial block (MP) is inserted as the final element to minimize the modeling errors. A relevant model identification method, based on an iterative algorithm, has been developed as well. The proposed architecture is used for the linearization of a commercial class-AB LDMOS RF PA by NXP Semiconductors, in wideband communication systems. Comparison of performance with the conventional generalized memory polynomial model (GMP) shows that the proposed model offers similar results, with its advantage consisting in the reduced number of parameters

GPR, a ground‐penetrating radar for the Netlander mission

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95485/1/jgre1563.pd

Digital Predistortion of Wideband Signals with Reduced Complexity Based on Feedback Wiener System

Digital predistortion (DPD) using baseband signals is commonly used for power amplifier linearization. This paper is devoted to this subject and aims to reduce DPD complexity. In this study, we propose a structure that allows to decrease the number of DPD parameters by using multiple blocks, with each one of them dedicated to characterizing the non-linear behavior and/or memory effects. Such a structure is based on the feedback Wiener system, involving a FIR filter used as a feedback path to reproduce the PA inverse dynamics. A memory polynomial block (MP) is inserted as the final element to minimize the modeling errors. A relevant model identification method, based on an iterative algorithm, has been developed as well. The proposed architecture is used for the linearization of a commercial class-AB LDMOS RF PA by NXP Semiconductors, in wideband communication systems. Comparison of performance with the conventional generalized memory polynomial model (GMP) shows that the proposed model offers similar results, with its advantage consisting in the reduced number of parameters

GPR, a ground‐penetrating radar for the Netlander mission

International audienceIn the coming decade, several missions are planned that will land on the surface of Mars landers or instrumented geophysical stations. Among the scientific objectives of these projects, one of the most important will be to unravel the many unknowns in the geological and hydrological history of the planet. The Netlander mission offers a unique opportunity to explore the interior of Mars, its subsurface, its atmosphere, and its distant environment from four landing sites that will be selected to offer a variety of different geophysical conditions. We have thus proposed to fly on these four landers a ground-penetrating radar (GPR) to explore the geological characteristics of the subsurface and search for water reservoirs down to a depth which may be sufficient to allow a possible detection of liquid water. We provide in this paper a short description of this radar which is based on a new concept to allow a 3-D imaging of the subsurface by determining the range and direction of the underground reflectors. In order to access to deep layers, it will operate at a low frequency of 2 MHz. Some results obtained by a numerical modeling of the radar operation in an electromagnetic model of the Martian subsurface are presented in order to illustrate the main capabilities of the radar. In the last section, preliminary results from an initial field test are reported. In addition to its primary goal as a ground-penetrating radar, the GPR will also be operated on Mars as an ionospheric sounder and, in a passive mode, as a HF receiver to measure the radio-electric background