Radiofrequency architectures and technologies for software defined radio

Six-port network is an interesting radiofrequency architecture with multiple possibilities. Since it was firstly introduced in the seventies as an alternative network analyzer, the six-port network has been used for many applications, such as homodyne receivers, radar systems, direction of arrival estimation, UWB (Ultra-Wide-Band), or MIMO (Multiple Input Multiple Output) systems. Currently, it is considered as a one of the best candidates to implement a Software Defined Radio (SDR). This thesis comprises an exhaustive study of this promising architecture, where its fundamentals and the state-of-the-art are also included. In addition, the design and development of a SDR 0.3-6 GHz six-port receiver prototype is presented in this thesis, which is implemented in conventional technology. The system is experimentally characterized and validated for RF signal demodulation with good performance. The analysis of the six-port architecture is complemented by a theoretical and experimental comparison with other radiofrequency architectures suitable for SDR. Some novel contributions are introduced in the present thesis. Such novelties are in the direction of the highly topical issues on six-port technique: development and optimization of real-time I-Q regeneration techniques for multiport networks; and search of new techniques and technologies to contribute to the miniaturization of the six-port architecture. In particular, the novel contributions of this thesis can be summarized as: - Introduction of a new real-time auto-calibration method for multiport receivers, particularly suitable for broadband designs and high data rate applications. - Introduction of a new direct baseband I-Q regeneration technique for five-port receivers. - Contribution to the miniaturization of six-port receivers by the use of the multilayer LTCC (Low Temperature Cofired Ceramic) technology. Implementation of a compact (30x30x1.25 mm) broadband (0.3-6 GHz) six-port receiver in LTTC technology. The results and conclusions derived from this thesis have been satisfactory, and quite fruitful in terms of publications. A total of fourteen works have been published, considering international journals and conferences, and national conferences. Aditionally, a paper has been submitted to an internationally recognized journal, which is currently under review

Four-Octave Six-Port Receiver and its Calibration for Broadband Communications and Software Defined Radios

This paper presents a software defined radio six-port receiver for a novel broadband mobile communications system. The prototype covers the frequency range from 0.3 GHz to 6 GHz, and operates with up to 100 MHz-wide channels. The multi-band and multi-mode demodulation capabilities of the six-port architecture have been experimentally demonstrated. The six-port receiver has been satisfactorily proved for high data rates (up to 93.75 Mb/s, limited by the available test instruments). An efficient six-port auto-calibration method suitable for large instantaneous bandwidth systems is presented and validated

Direct Baseband I-Q Regeneration Method for Five-Port Receivers Improving DC-offset and Second-Order Intermodulation Distortion Rejection

Six/Five-port architecture has advantages compared to conventional receiver architectures, especially for high frequencies and high data rate applications. However, it requires two/one additional baseband outputs and a calibration process to recover the original signal. While this problem is resolved in conventional six-port configurations, a solution is needed for five-port architectures. We propose an I/Q regeneration method based on the use of a simple analog circuit, eliminating one baseband output. The structure of this circuit derives from a mathematical formulation, which is presented in this paper. The validity of the method has been experimentally proved in a five-port receiver prototype. In addition, its capacity to reduce the DC-offset and second-order intermodulation distortion (IMD2) has been demonstrated

Direct Baseband I-Q Regeneration Method for Five-Port Receivers Improving DC-offset and Second-Order Intermodulation Distortion Rejection

<p>Six/Five-port architecture has advantages compared to conventional receiver architectures, especially for high frequencies and high data rate applications. However, it requires two/one additional baseband outputs and a calibration process to recover the original signal. While this problem is resolved in conventional six-port configurations, a solution is needed for five-port architectures. We propose an I/Q regeneration method based on the use of a simple analog circuit, eliminating one baseband output. The structure of this circuit derives from a mathematical formulation, which is presented in this paper. The validity of the method has been experimentally proved in a five-port receiver prototype. In addition, its capacity to reduce the DC-offset and second-order intermodulation distortion (IMD2) has been demonstrated.</p