Scuola di Dottorato in Scienze ed Ingegneria dell'Informazione
Dottorato di Ricerca in Ingegneria Elettronica Informatica e delle Telecomunicazioni
Short course on:
“RF electronics for wireless communication and remote sensing systems”
27th June, 30thJune 2011, Facoltà di Ingegneria, Viale Risorgimento 2, Bologna
Summary
The main technological issues and circuit design challenges arising in the development and manufacturing of the RF front-end electronics for the next generation (terrestrial or space-born)radio communication and remote sensing systems will be synthetically outlined, with the aim of also pointing out both the specific design tool requirements and a number of related research topics.
Actually, the ever-increasingcomputational power of DSP electronics allows for the digital implementation of a relevant number of otherwise analogue signal processing functions (e.g. not only relatively low-frequency mo/demodulation, but also fully digital filtering and processing of high-frequency IF signals),with all the advantages of the Software Defined Radio approach: flexibility,re-configurability,frequency agility, reliable fault-tolerant design.
However, the main system performance parameter (e.g. S/N ratio, bit error rate, power consumption,reliability) still strongly depend on the characteristics (e.g. non-linear distortion, output power, noise, dynamic range, interference resistance, power added efficiency) of the RF electronic circuits playing a fundamental role in the receiver and transmitter front-ends of wireless systems:Power Amplifiers, Low-Noise Amplifiers, Voltage Controlled Oscillators, mixers, Frequency Synthesizers, fast A/D and D/A converters.This is particularly true for the next generation wireless systems, where much stronger constraints onbroad-band RF circuit performance derive from the performance requirements of high-capacity, highly-flexible, compact, multiple input/output wireless systems.
Thus, byconsidering specific case studies, special attention will be paid to noise, non-linear distortion and interference resistance in broad-band LNAs and A/D conversion channels, phase-noise in VCOs for frequency synthesizers, and the trade-off issues between non-linear distortion, output power and power-added efficiency in RF power amplifiers. Different application scenarios, with associated circuit performance requirements and technological solutions in the areas of terrestrial communication systems and satellite remote sensing/communication payloads, will be described by experts from industrial R&D labs.
The short course is organized as a set of integrated seminars according to the following programme:
Fernando Marchetti and Marziale Feudale-Thales Alenia Space
Remote Sensing: from Earth Observation to Space Exploration
This presentation provides an overview of the satellite remote sensing equipment used in Earth Observation and Planetary Exploration. After recalling the basics of operation and different application scenarios of satellite payloads for remote sensing, the present and future architectures of the RF front-ends of Earth-Observing and Planetary Exploration Radars (SARs in particular) and Radiometerswill be outlined, by pointing out the main requirements in the design of the basic building blocks (Receivers, Up/Down Converters, Transmitters, Frequency Generators,..) of the satellite RF equipment for radar payloads.
Present and future technological issues in the manufacturing of satellite RF payloads will be outlined, by also considering the specific requirements (reliability, radiation resistance, power consumption, weight, ..) associated with space-born electronic equipment.
Alessandra Costanzo and Diego Masotti, Università di Bologna
Integration of Nonlinear, Radiation, and Propagation Analysis Techniques for circuit-levelDesign of entire RF links
The lecture will describe a CAD procedure for the circuit-level simulation of entire modern RF links, such as SISO (Single Input Single Output), MIMO (Multiple Input Multiple Output), and UWB (Ultra Wide Band) links. Due to the miniaturization of such systems, an integrated analysis/ design at the circuit level allows to accurately account for the nonlinear interaction among subsystems. The lecture will first describe the main building blocks to be concurrently analyzed.
A SISO link example will be first described and the simulation from the transmitter to the receiver intermediate-frequency ports is considered by means of nonlinear analysis coupled with the electromagnetic characterization of the transmitter and receiver front ends. In the MIMO case, the multiple transmitting and receiving antennas are described as one multiport radiating systems, by EM analysis, thus accounting for mutual couplings in terms of the frequency-dependent near-field and far-field performance. Furthermore the transmitters are treated as a unique nonlinear system loaded by the multiport antenna, and analyzed again by nonlinear circuit techniques. The same is done for the set of receivers.Both in SISO and MIMO cases, the connection between transmitters and receivers is established by means of the following steps: i) the radiated far-field is evaluated by EM analysis, and the field incident on the receiver side is computed by an available ray tracing technique; ii) EM theory is then used to describe the receiving (single- or multi-port) antenna as a linear active single- or multi-port network. BER computation and minimization is demonstrated for the first time at the circuit level with affordable computational efforts.
Similar simulation approach will be applied to the analysis of pulse-UWB receiver front ends in the presence of interfering communication signals. Interference effects on the nonlinear regime of UWB receivers and accurate circuit-level prediction of receiver sensitivity and channel capacitance will be discussed as the results of this analysis.
Eleonora Franchi, Antonio Gnudi, MarcoGuermandi, Università di Bologna
Frequency synthesizers for RF transceivers
-Short introduction to frequency synthesis for integrated RF transceivers.
-Phase locked-loops (PLL): architecture, waveforms, building blocks (phase-frequency detectors, charge pump, loop-filter, VCO, frequency dividers).
-Modelling of PLL in the frequency and time domain; Noise in PLLs.
-Design examples:
1) Synthesizer for UWB receivers
2) Synthesizer and VCOs for fully-integrated reconfigurable multi-standard transceivers: high tuning-range VCO, fractional-N synthesizers with techniques for spurious compensation and increased linearity.
Alberto Santarelli, Fabio Filicori, Università di Bologna
Non linear distortion and dynamic range issues in the design of microwave electronics for communication and remote sensing systems
-Non linear distortion, noise and dynamic-range issues in the basic circuits used as the building blocks in RF electronics for wireless communication and remote sensing systems.
- Trade-off issues between nonlinear distortion, output power and power added efficiency in the design/optimization of highly-linear microwave power amplifiers for high capacity radio links.
-Basics of new generation electron devices and modeling/design tools for low-distortion, high-dynamic-range microwave circuit design.
Corrado Florian, Università di Bologna
Nonlinear noise in RF and microwave communication front-ends: theory, modelling and practical examples
Electrical noise is a limiting factor for the performance of communication circuits, both under small- and large-signal operation. This contribution will focus on the effects of nonlinear noise on the performance of oscillators and low noise amplifiers. Special emphasis will be given to oscillator circuits, covering some basic aspects of their design and describing the different topologies and technologies adopted in their implementation. The main topics covered by the seminar are:
- Basics of noise in electronics components: broad-band noise and low-frequency noise in linear and non linear operation.
- Oscillator design: small-signal and large-signal analysis; different oscillator topologies and technologies: quartz-stabilized, DRO, VCO, differential and push-push architectures.
- Noise in oscillators: Phase Noise definition, generation mechanism and effects; PNminimization techniques.
-Noise in amplifiers: Noise Figure in small-signal operation and nonlinear operating conditions; non-linear noise generation, characterization and modelling for Low-Noise Amplifiers in the presence of strong interfering signals.
Pier Andrea Traverso, Università di Bologna
RF Analogue-to-Digital conversion channels
Receiver front-ends for a wide family of both terrestrial and satellite communication/sensing systems take advantage of the ever-increasing performance of A/D converters and related circuits. The recent improvements in terms of real-time sampling frequency, vertical resolution, linearity and reliability allow for the design and implementation of broad-band A/D conversion channels directly at RF, with a significant reduction of the frequency down-conversion analogue circuits between the antenna system and the section at which the signals are converted to digital. In this talk the following topics will be addressed:
-Basics of analogue-to-digital conversion techniques. Architectures for fast A/D Converters (ADCs) oriented to the sampling and quantization of RF signals.
-Experimental characterization procedures and performance evaluation of A/D conversion channels.
-Non-linear dynamic modelling and algorithmic compensation of the non-idealities within RF A/D conversion channels using a modified Volterra-based approach.
Rudi Paolo Paganelli, Istituto di Elettronica e di Ingegneria dell'Informazione e delle Telecomunicazioni-CNR
Microwave power amplifiers for satellite remote sensing and communication
Design issues of high-efficiency power amplifiers formicrowave transmitters in satellite payloads are dealt with by examining the most important figures of merit in relation to some typical transistor operating classes (A, AB, B, etc..). After considering a nearly ideal active device in the assessment of general criteria for load-line and operating condition optimization, also non-ideal effects in power electron devices will be considered. Possibility of achieving higher levels of efficiency by adopting a near-switch-mode transistor operation even at microwave frequencies will be also examined. Power dissipation, maximum channel temperature for reliable operation and thermal stability problems will also be discussed. Two practical examples of HPA design will be illustrated for two different technologies (pHEMT, HBT) and classes of operation (AB, E).
Finally, examples of power amplifier architectures optimizing efficiency or linearity in applications with advanced modulation schemes are briefly illustrated.