Gerald Ulbricht

Eine Sendestufe, die gemas dem Envelope-Restoration-Prinzip arbeitet, umfast eine Einrichtung (14) zum Bereitstellen einer Amplitudendarstellung und einer Phasendarstellung eines zu sendenden Amplituden- und Phasen-modulierten Signals sowie eine Phasenregelschleife (PLL) mit einem Vorwartskopplungszweig (16) und einem Ruckkopplungszweig (17) sowie eine Verstarkungssteuerungseinrichtung (21), die ausgebildet ist, um die Amplitudendarstellung in ein Verstarkungssteuerungssignal umzusetzen, das in den Verstarkungssteuerungseingang eines nicht-linearen Leistungsverstarkers einspeisbar ist. In dem Vorwartskopplungszweig (16) ist ein Digital/Analog-Wandler angeordnet. Ferner ist in dem Ruckkopplungszweig (17) ein Analog/Digital-Wandler angeordnet, so das der Phasendetektor der Phasenregelschleife in digitaler Form ausgefuhrt ist. Durch einen moglichst grosen Anteil an digitaler Signalverarbeitung wird eine preisgunstige implementierbare und exakt arbeitende Sendestufe erhalten.

Polar transmitters amplify non-constant envelope signals with high power efficiency. Thus they are especially advantageous for battery-powered wireless equipment. In this paper a polar GSM/EDGE transmitter is introduced, which uses an off-the-shelf GMSK PA as a non-linear high-efficient amplifier, thereby only minor modifications of the analog RF circuit compared to a 2G GSM mobile are necessary. An adaptation of frequency dependent group delay in the phase path minimizes amplitude modulation bandwidth requirements. Employing a memory predistorter, -61 dBc ACPR (adjacent channel power ratio) was achieved.

A method for generating an output signal (160, 60) based on a complex-modulated input signal (102) in an amplitude signal (104, 250A) and a phase signal (106, 250P) is disassembled, the one Amplitudensignalweg (120, 220) and a Phasensignalweg (130, 230) are provided, wherein a total group delay distortion is caused in one of the signal paths comprises a first group delay distortion, which is caused by a circuit element in the first signal, and wherein (160, 260) the output signal based on the signals at an output of the amplitude signal path (120, 220) and an output of the phase signal path (130, 230) by means of a combiner (160) by the EER method (Envelope elimination and Restoration envelope removal and recovery) is generated, said method comprises the step of: Introducing a second group delay distortion in the Phasensignalweg (130, 230), wherein the second group delay distortion is dimensioned such that the second group delay distortion of the first group delay distortion, or the...

Means (100) for generating a correction signal for linearizing an output signal of a non-linear element having the following feature: To generate a correction signal generator (110), which is designed based on a superposition of a reference digital signal (130) and a superimposed output signal a correction signal (140), the superposed output signal on a superposition of the output signal (102) and an analog reference signal ( 120) is based, wherein the non-linear element is adapted to generate the output signal (102) based on an input signal and said digital reference signal (130) and the analog reference signal (120) based on the input signal.

A Current Mode Class D (CMCD) power amplifier at 900 MHz is presented. After a theoretical analysis, a class D amplifier is designed, simulated and afterwards assembled and characterized. Thereby, a maximum drain efficiency of 80.6%, and a maximum power added efficiency (PAE) of 72.8% at a switching frequency of 864 MHz, and an output power of 28.2 dBm were obtained. A linear class A amplifier using the same transistor exhibits a drain efficiency of 48.9% and 48.0% PAE at a comparable output power. An analysis of the reverse intermodulation distortion (IMD) of the switched-mode class D amplifier in comparison to the class A amplifier shows a 15dB improvement of the third order intermodulation ratio. To the authors' knowledge, this is the first practical verification of the superior reverse intermodulation performance of switched-mode amplifiers.

In einem Feedforward-Verstarker (400) erfolgt die Erzeugung eines digitalen Korrektursignals (140) mit Hilfe zweier analoger Signale (102,120) und eines digitalen Signals (130). Dabei wird zunachst ein Teil des analogen Ausgangssignals (102) eines nicht-linearen Elements (10) ausgekoppelt (102) und einem ersten Kombinierer (43) zugefuhrt. Eine Kopie des analogen Eingangssignals wird uber einen Verzogerer (42) einem zweiten Eingang des ersten Kombinierers (43) zugefuhrt. Der Ausgang des ersten Kombinierers (43) ist uber einen A/D-Wandler (32) mit einem Eingang eines zweiten Kombinierers (16) verbunden. Eine Kopie des digitalisierten Eingangssignals wird uber einen Amplitudensteller (13), einen Phasensteller (14) sowie einem Verzogerer (15) einem zweiten Eingang des zweiten Kombinierers (16) zugefuhrt. Am Ausgang des zweiten Kombinierers (16) steht nun das gewunschte Korrektursignal (140) zur Verfugung.

ABSTRACT This paper describes a novel architecture for a wideband HF power amplifier for multi-carrier application, its target performance and in more detail the use of a vector phase shifter as a critical building block. The proposed architecture is based on a combination of modified feedforward techniques and digital pre-conditioning.

ABSTRACT This paper describes the architecture and performance of a demonstrator for a wideband multi-carrier power amplifier for use as a powerbank in shipboard HF communications. The demonstrator was built and evaluated to prove an advanced concept comprising two nested feedforward linearizers for suppressing unwanted emissions associated with intermodulation and harmonic distortion.

DE 102008052172 A1 UPAB: 20100430 NOVELTY - The device (100) has a correction signal generator (110), which is designed to produce a correction signal (140) based on a superimposition of a digital reference signal (130) and a superimposed output signal. The superimposed output signal is based on the superimposition of the output signal (102) and an analog reference signal (120). DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a system for linearizing an output signal of a non-linear element; (2) a method for producing a correction signal for linearizing an output signal of a non-linear element; (3) a method for linearizing an output signal of a non-linear element; and (4) a computer program. USE - Device for producing a correction signal for linearizing an output signal of a non-linear element in a system (Claimed). ADVANTAGE - The device has a correction signal generator, which is designed to produce a correction signal based on a superimposition of a ...

This paper presents the detailed design and the key system performance results of a comprehensive laboratory demonstrator for a broadband Ka-band multi-beam satellite system exploiting the new DVB-S2 standard with adaptive coding and modulation (ACM). This complete demonstrator allows in-depth verification and optimization of the ACM techniques applied to large satellite broadband networks, as well as complementing and confirming the more theoretical or simulation-based findings published so far. It is demonstrated that few ACM configurations (in terms of modulation and coding) are able to efficiently cope with a typical Ka-band multi-beam satellite system with negligible capacity loss. It is also demonstrated that the exploitation of ACM thresholds with hysteresis represents the most reliable way to adapt the physical layer configuration to the spatial and time variability of the channel conditions while avoiding too many physical layer configuration changes. Simple ACM adaptation techniques, readily implementable over large-scale networks, are shown to perform very well, fulfilling the target packet-error rate requirements even in the presence of deep fading conditions. The impact of carrier phase noise and satellite nonlinearity has also been measured. Copyright © 2009 John Wiley & Sons, Ltd.

ABSTRACT A Current Mode Class D (CMCD) power amplifier at 900 MHz is presented. After a theoretical analysis, a class D amplifier is designed, simulated and afterwards assembled and characterized. Thereby, a maximum drain efficiency of 80.6%, and a maximum power added efficiency (PAE) of 72.8% at a switching frequency of 864 MHz, and an output power of 28.2 dBm were obtained. A linear class A amplifier using the same transistor exhibits a drain efficiency of 48.9% and 48.0% PAE at a comparable output power. An analysis of the reverse intermodulation distortion (IMD) of the switched-mode class D amplifier in comparison to the class A amplifier shows a 15dB improvement of the third order intermodulation ratio. To the authors' knowledge, this is the first practical verification of the superior reverse intermodulation performance of switched-mode amplifiers.