The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Gottfried Magerl - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of the imbalance effects in Direct Conversion transmitters and receivers
2011 Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, 2011Co-Authors: Michael Ernst Gadringer, Thomas Faseth, Gottfried MagerlAbstract:Although Direct Conversion transmitters and receivers share the same structure certain differences in their behavior can be found. These differences result in diverse performance limitations. This paper derives a linear model of Direct Conversion transmitters and receivers. Based on this model methods to extract the frequency dependent characteristics are introduced and compensators are suggested. By applying these techniques to a custom transmitter and receiver setup the achievable imbalance suppressions are demonstrated and the derived performance improvements are compared.
-
Phase Dependent Distortion in Direct Conversion Transmitters
IEEE Transactions on Microwave Theory and Techniques, 2011Co-Authors: Michael Ernst Gadringer, Wolfgang Bosch, Gottfried MagerlAbstract:The impairments and nonlinear (NL) distortion generated by the analog quadrature modulator in a Direct Conversion transmitter affect the performance of a transmission system. These effects cause input signal dependent gain variations at the low-pass equivalent I/Q-modulator output. The aim of this paper is to analytically derive the relationship between the mean transmitter gain and the tone phases of single- or two-tone excitation signals. This relationship is separately evaluated for the different distortion sources in the Direct Conversion transmitter. It will be shown that only two-tone signals with frequencies symmetrical to DC are able to excite these phase-dependent gain variations. Additionally, the conditions for the presence of the distortion mechanisms are highlighted. Using measurements of an experimental transmitter setup, the validity of the derived results is shown. The presence of phase-dependent gain changes were also measured when applying a DC-symmetric multi-tone signal.
-
Characterization and Modeling of Direct Conversion Transmitters
2008 38th European Microwave Conference, 2008Co-Authors: Michael Ernst Gadringer, Christian Schuberth, Gottfried MagerlAbstract:This work presents a description of a Direct Conversion transmitter excluding the power amplifier. The model predicts the impact of the even- and odd-order distortion introduced by the analog baseband signal processing and the mixer together with linear effects. The model is parameterized by measuring the response of a Direct Conversion transmitter onto single- and two-tone signals. By comparing the response of the transmitter to the model output the performance of the presented approach is verified.
Michael Ernst Gadringer - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of the imbalance effects in Direct Conversion transmitters and receivers
2011 Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, 2011Co-Authors: Michael Ernst Gadringer, Thomas Faseth, Gottfried MagerlAbstract:Although Direct Conversion transmitters and receivers share the same structure certain differences in their behavior can be found. These differences result in diverse performance limitations. This paper derives a linear model of Direct Conversion transmitters and receivers. Based on this model methods to extract the frequency dependent characteristics are introduced and compensators are suggested. By applying these techniques to a custom transmitter and receiver setup the achievable imbalance suppressions are demonstrated and the derived performance improvements are compared.
-
Phase Dependent Distortion in Direct Conversion Transmitters
IEEE Transactions on Microwave Theory and Techniques, 2011Co-Authors: Michael Ernst Gadringer, Wolfgang Bosch, Gottfried MagerlAbstract:The impairments and nonlinear (NL) distortion generated by the analog quadrature modulator in a Direct Conversion transmitter affect the performance of a transmission system. These effects cause input signal dependent gain variations at the low-pass equivalent I/Q-modulator output. The aim of this paper is to analytically derive the relationship between the mean transmitter gain and the tone phases of single- or two-tone excitation signals. This relationship is separately evaluated for the different distortion sources in the Direct Conversion transmitter. It will be shown that only two-tone signals with frequencies symmetrical to DC are able to excite these phase-dependent gain variations. Additionally, the conditions for the presence of the distortion mechanisms are highlighted. Using measurements of an experimental transmitter setup, the validity of the derived results is shown. The presence of phase-dependent gain changes were also measured when applying a DC-symmetric multi-tone signal.
-
Characterization and Modeling of Direct Conversion Transmitters
2008 38th European Microwave Conference, 2008Co-Authors: Michael Ernst Gadringer, Christian Schuberth, Gottfried MagerlAbstract:This work presents a description of a Direct Conversion transmitter excluding the power amplifier. The model predicts the impact of the even- and odd-order distortion introduced by the analog baseband signal processing and the mixer together with linear effects. The model is parameterized by measuring the response of a Direct Conversion transmitter onto single- and two-tone signals. By comparing the response of the transmitter to the model output the performance of the presented approach is verified.
Abdolali Abdipour - One of the best experts on this subject based on the ideXlab platform.
-
Direct Conversion receivers using multiport structures for software-defined radio systems
IET Microwaves Antennas & Propagation, 2007Co-Authors: Mehrbod Mohajer, Abbas Mohammadi, Abdolali AbdipourAbstract:An analytical assessment for multiport structures as Direct Conversion receivers is presented. A new Direct-Conversion receiver based on a novel five-port structure suitable for software-defined radio applications is proposed. The five-port architecture provides some advantages compared with previous architectures. Numerical and microwave simulations have been conducted to show its capabilities as a Direct demodulator. The proposed five-port has been constructed and the measured results indicate that the five-port receiver introduced can be used effectively as a software-defined radio receiver.
-
A software defined radio Direct Conversion receiver
The European Conference on Wireless Technology 2005., 1Co-Authors: Mehrbod Mohajer, Abbas Mohammadi, Abdolali AbdipourAbstract:In this paper, we present a new Direct Conversion receiver based on multi-port structures that are very suitable for software defined radio applications. The proposed receiver is a five-port architecture which provides some advantages in compare to the previous architectures. The microwave simulations have been conducted to show its abilities as a Direct demodulator. Meanwhile, the measured results indicate that the introduced five-port can be effectively used as a software defined radio receiver
T. Itoh - One of the best experts on this subject based on the ideXlab platform.
-
a reconfigurable active retroDirective Direct Conversion receiver array for wireless sensor systems
International Microwave Symposium, 2001Co-Authors: R.y. Miyamoto, Yongxi Qian, T. ItohAbstract:A reconfigurable active retroDirective/Direct Conversion receiver array is presented. The system can serve as both a retroDirective array transponder and a Direct Conversion receiver simply by changing the frequency of the LO applied to the mixers. In the retroDirective array mode, the circuit provides 20 dB gain and 20 dB RF-IF isolation. The mixers perform phase-conjugation and modulation simultaneously. When operating as a Direct Conversion receiver, both I and Q channels are successfully recovered.
-
A reconfigurable active retroDirective/Direct Conversion receiver array for wireless sensor systems
2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157), 1Co-Authors: R.y. Miyamoto, Yongxi Qian, T. ItohAbstract:A reconfigurable active retroDirective/Direct Conversion receiver array is presented. The system can serve as both a retroDirective array transponder and a Direct Conversion receiver simply by changing the frequency of the LO applied to the mixers. In the retroDirective array mode, the circuit provides 20 dB gain and 20 dB RF-IF isolation. The mixers perform phase-conjugation and modulation simultaneously. When operating as a Direct Conversion receiver, both I and Q channels are successfully recovered.
-
Direct Conversion receiver for digital beamforming at 8.45 GHz
2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No.01CH37157), 1Co-Authors: Kazutomi Mori, Hiroyuki Arai, Y. Qian, T. ItohAbstract:Direct Conversion receiver for digital beamforming (DBF) at 8.45 GHz for next generation wireless telecommunication is presented. In this proposed system, the quadrature hybrid and tuning circuit are partially constructed by digital techniques for the simplification of hardware. We demonstrate the Direct Conversion FET second harmonic mixers without DC bias at RF part. We also examine this proposed receiver's ability to function as a digital beam former. In this result, the digital beam forming can be realize that side lobe level is below -10 dB and the half power beam width is about 60/spl deg/, in case of scanning range is limited /spl plusmn/20/spl deg/ by using this proposed receiver.
R.k. Loper - One of the best experts on this subject based on the ideXlab platform.
-
A tri-phase Direct Conversion receiver
IEEE Conference on Military Communications, 1Co-Authors: R.k. LoperAbstract:A Direct Conversion receiver architecture that utilizes three channels separated in phase by 120 degrees , instead of the traditional two channels in phase quadrature, is described. The disadvantages of using Direct Conversion receives, including the difficulty of obtaining the necessary accuracy of gain balance and phase quadrature between the in-phase and quadrature phase channels are discussed, and the theory behind the tri-phase Direct Conversion receiver is presented. Test data obtained from a breadboard receiver are presented. >
