Limitation of a Five-Port Reflectometer using planar elliptic couplers for UWB applications

In this paper, we present the design of ultra wideband (UWB) planar Five-Port Reflectometer using the elliptic coupler which has the advantage to offer a wide bandwidth compared to the hybrid one. The elliptic coupler and the five-port circuit were designed and simulated in the 1.5 to 3.5 GHz band using ADS software of Agilent. An analytical calculus and simulation results of a five-port circuit using elliptic coupler demonstrate limitations of this structure

A Software Defined Radio Platform with Direct Conversion: SOPRANO

A new software defined radio platform with multiport-based direct conversion is proposed, named SOPRANO (Software Programmable and Hardware Reconfigurable Architecture for Network). The main features of SOPRANO are a high-level design methodology for digital circuits, a new mixer-less direct conversion method, and software algorithms for multi-band and multi-mode operation. We built the first prototype SOPRANO 1.0, which was able to receive PSK and QAM signals with two different carrier frequencies at 2.45 GHz and 5.25 GHz by changing signal processing software

Optoelectronic oscillators for communication systems

We introduce and report recent developments on a novel five port optoelectronic voltage controlled oscillator consisting of a resonant tunneling diode (RTD) optical-waveguide integrated with a laser diode. The RTD-based optoelectronic oscillator (OEO) has both optical and electrical input and output ports, with the fifth port allowing voltage control. The RTD-OEO locks to reference radio-frequency (RF) sources by either optical or electrical injection locking techniques allowing remote synchronization, eliminating the need of impedance matching between traditional RF oscillators. RTD-OEO functions include generation, amplification and distribution of RF carriers, clock recovery, carrier recovery, modulation and demodulation and frequency synthesis. Self-injection locking operation modes, where small portions of the output electrical/ optical signals are fed back into the electrical/optical input ports, are also proposed. The self-phase locked loop configuration can give rise to low-noise high-stable oscillations, not limited by the RF source performance and with no need of external optoelectronic conversion

W-Band GaAs HEMT MMIC Subharmonically Pumped Diode Mixers with 20 GHz IF Bandwidth

Two subharmonically pumped (SHP) diode mixers are designed for wideband W-band RF frequencies, fixed LO frequency operation. These mixers are fabricated on a 4-mil substrate using 0.1- µµµµm GaAs MMIC process. Both simulation and test results show that the mixers are with 12.25 and 11.75 dB average conversion losses, respectively. Both mixers have IF bandwidth wider than 20 GHz. The conversion loss flatness of the symmetric circuit is within ±1.25 dB. To our knowledge, these are the state-of-the-art result on low-conversion-loss wideband MMIC SHP diode mixers

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

Passive opto-antenna using air-filled substrate-integrated-waveguide technology

In this contribution, we propose a novel extensive full-wave/circuit cosimulation model to analyze the performance of an opto-electronic fully passive downlink remote antenna unit. The vertical-cavity surface-emitting laser, the optical back-to-back connection, the photodetector, the lumped/distributed matching network, and the air-filled substrate-integrated-waveguide antenna are described in a single, complete model, which also incorporates the spurious radiation by the distributed matching network and any remaining impedance mismatch of the antenna

240-GHz Reflectometer-Based Dielectric Sensor With Integrated Transducers in a 130-nm SiGe BiCMOS Technology

This article presents a reflectometer-based on-chip dielectric sensor with integrated transducers at 240 GHz. The chip simplifies the measurement of a vector network analyzer (VNA) to sense the incident and reflected waves by using two heterodyne mixer-based receivers with a dielectric sensing element. Radio frequency (RF) and local oscillator (LO) submillimeter waves are generated by two frequency multiplier chains, respectively. Two back-to-back identical differential side-coupled directive couplers are proposed to separate the incident and reflected signals and couple them to mixers. Both transmission line and coplanar stripline transducers are proposed and integrated with reflectometer to investigate the sensitivity of dielectric sensors. The latter leads to a larger power variation of the reflectometer by providing more sufficient operating bands for the magnitude and phase slope of S11 . The readout of the transducers upon exposure to liquids is performed by the measurement of their reflected signals using two external excitation sources. The experimental dielectric sensing is demonstrated by using binary methanol–ethanol mixture placed on the proposed on-chip dielectric sensor in the assembled printed circuit board. It enables a maximum 8 dB of the power difference between the incident and reflected channels on the measurement of liquid solvents. Both chips occupy an area of 4.03 mm 2 and consume 560 mW. Along with a wide operational frequency range from 200 to 240 GHz, this simplified one-port-VNA-based on-chip device makes it feasible for the use of handle product and suitable for the submillimeter-wave dielectric spectroscopy applications

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

A good conversion loss and a very high LO-to-RF isolation of 24-GHz single balanced mixer for RF front-end receiver

This work describes the design, analysis and fabrication of a 24-GHz microwave single balanced down-conversion mixer based on Schottky diode, hybrid ring coupler and a wide and deep stopband low-pass filter (LPF). The LPF is composed of three uniform defected ground structures along with a compensated microstrip line. The selected frequencies are 24.125 GHz for RF signal and 24 GHz for LO signal. When the LO and RF signals are injected as 10 dBm and 0 dBm respectively, a conversion loss of 12.85 dB with an LO-to-RF isolation greater than 38 dB is obtained. The measured results agree well with the simulated results and the reported design