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Presenter:	Dr. Rowan Gilmore University of Queensland
Dates:	12–13 November, 2009
Venue:	Wellington, New Zealand

About Fundamentals of RF System Design and Simulation

The increasing level of complexity and circuit integration in modern radio systems requires not only understanding of the design of circuits, but of subsystems as well. RF circuits are typically designed to meet power, efficiency, gain, linearity and noise specifications when driven by single or two-tone excitations; whereas the RF system is driven by much more complex signals and must be designed to meet specifications like bit error rate, dynamic range, and minimum detectable signal in the presence of interferers. Only through understanding the interactions between circuits, and through careful simulation, can all the specifications be reconciled.

This course will focus on tradeoffs in designing wireless systems, and show how to seamlessly move between both the circuit and system level in radio transceivers and other RF systems. We do this by looking at typical radio architectures, exploring the design tradeoffs, and simulating at both the circuit and system level. The course treats digitally coded signals in RF and IF components, and explores the compromises that are inherent in the design of a radio transceiver. From the RF perspective, the need to minimize interference from nearby unwanted stronger signals and to allow detection of a desired signal in noise is critical. Avoiding corruption of other signals sharing the spectrum is equally critical. Achieving both together is not so simple! In wireless LAN for instance, tradeoffs made to solve one problem, like multi-path reception, have placed tight constraints on other parts of the system, such as the linearity of the power amplifier.

We will interactively simulate a double super-heterodyne, dual-band radio receiver, as well as multiple components. This provides the opportunity to explore 'what if?' scenarios. To benefit most, bring your own laptop computer and, prior to attending, obtain a free trial license of the Visual Systems Simulator (VSS) from Applied Wave Research at www.appwave.com.

Course Outcomes

On completion of the course, you will be:

• familiar with the basic air-interface specifications of a mobile radio system, and understand how the key parameters relate to RF hardware
• able to simulate various types of RF and IF systems and component interactions
• able to specify the key components within a system to meet its RF requirement
• comfortable with reading integrated circuit data sheets for wireless systems, their architecture, and specifications
• able to understand the compromises in choosing architectures and circuits to meet given system requirements. 

Brief Course Outline

Day One

Introduction to Radio Systems and Digital Communications
We start by reviewing digital wireless communications and a variety of modulation formats. We look at the upconversion and downconversion processes in typical receiver and transmitter architectures, and the effects of filtering.

• Revision of Coding and Modulation Formats
• Baseband Filtering
• Typical Receiver System Architectures: Direct conversion, superheterodyne, dual conversion superheterodyne

Characterization and Measurement of Receivers

• Noise in Receivers Selectivity, Sensitivity and Minimum Detectable Signal
• Nonlinearities and Third-Order Intermodulation Distortion
• Reception in the Presence of Interferers
• Dynamic Range and How to Improve It With AGC

Day Two

We will look at a simplified form of the air-interface specification for a typical radio system. This describes the overall radio system requirements and enables multiple system operators to co-exist and interoperate. We will examine the basic system parameters that have to be measured - parameters such as noise, distortion, sensitivity, selectivity, and interference.

Characterization and Measurement of Transmitters

• Power and Harmonic Distortion
  
• Spurious Products
• ACPR, Spectral Regrowth and Linearity
• Efficiency
  

Next, we will see how these system parameters can be met by assembling a number of components. We will turn to their data sheets to discover how each is characterized, and examine the tradeoffs involved in selecting them. We will extract key defining features that describe the behavior of each circuit, and then simulate both the component and the system in the systems simulator.  

Simulation of a Dual-band Superhet Radio Receiver

• Spreadsheet-based Linear Systems Analysis
• Calculation of Sensitivity and Dynamic Range
• Systems SimulationAGC to Increase the Dynamic Range
• Effect of Changing the Gain, Intercept Point, and Filtering
  

System considerations for Amplifiers, Mixers, and Oscillators 

• Design Tradeoffs between Linearity, Power, and Efficiency Classes of Amplifier Operation
  
• Simulation of Spectral Regrowth with Different Modulation Formats Phase Noise in Oscillators
  
• Calculating Allowable Phase Noise from System Specifications
  
• I -Q Modulators and the importance of quadrature

Cancellation Policy

At least four weeks notice is required for cancellation of a place in a short course for full reimbursement. If cancellation is later than 4 weeks then the place can either be given to another person or the registrant can be provided with a credit towards other NICTA training.