RF Design: Applied Techniques

Course 248

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Summary

This new course incorporates the most popular topics from Applied RF Techniques 1 and 2 in a 5-day format. The material presented provides participants with the critical tools to design, analyze, test, and integrate linear and nonlinear transmitter and receiver circuits and subsystems.

Impedance matching is vitally important in RF systems and we use both graphical (Smith Chart ) and analytical techniques throughout the course. We also examine discrete and monolithic component models in their physical forms, discussing parasitic effects and losses, revealing reasons why circuit elements behave in surprising manners at RF. Filters, resonant circuits and their applications are reviewed through filter tables and modern synthesis techniques, leading into matching networks and matching filter structures. Since wires and printed circuit conductors may behave as transmission line elements, we also cover microstrip and stripline realizations. 2D and 2.5D electromagnetic field simulators are used in the course to illustrate transmission line behavior and component coupling effects.

In the area of active circuits, we first examine fundamental limitations posed by noise and distortion. The next topic is small-signal linear amplifier design, based on scattering parameter techniques, considering input/output match and gain flatness RF stability is examined both with S-parameters and also with the Nyquist test using nonlinear device models. Since DC biasing affects RF performance, we review active and passive bias circuits and see how they can be combined with impedance matching circuits. Another important consideration is circuit layout, therefore we look at problems caused by coupling, grounding and parasitic resistance. Narrow and broadband designs are compared, using lossless and lossy impedance matching as well as feedback circuits. Low-noise amplifier design is illustrated, discussing trade-offs among gain flatness, noise, RF stability, and impedance match. Harmonic and inter-modulation performance is also examined. Performance trade-offs of balanced amplifiers are viewed. The course concludes by examining large-signal and ultra wideband feedback amplifiers.

Circuit level engineers will master the latest linear and nonlinear design techniques to both analyze and design transceiver circuits. System engineers will examine block level circuit functions; learn the performance limits and how to establish specifications. Test engineers will learn how to test and evaluate circuits. Transceiver circuits to be covered include power amplifiers, oscillators ( PLL, VCO, etc. ) and the critical receiver elements. Receiver architecture and synthesizer design to meet critical requirements will be presented. Techniques to successfully integrate circuit functions at the system level will be discussed. Students are encouraged to bring their laptop computers to class. The design software available for use in this public course is from NI (formerly AWR).

Learning objectives

Upon completing the course you will be able to:

• Describe RF circuit parameters and terminology
• Match impedances and perform transformations
• Understand Impedance matching, component models, and PCB layout issues
• Design filters with lumped and distributed components
• Predict RF circuit stability and stabilize circuits
• Design various RF amplifiers: small-signal, low-noise, and feedback
• Understand and quantify nonlinear effects of transmit and receive systems
• Use CAD models to analyze/design circuits
• Design low noise and highly linear amplifiers
• Understand receiver performance parameters and modulation techniques
• Design signal sources using PLL ( phased lock loop ) techniques
• Explain and design VCOs and stable oscillators

Target Audience

The course is designed for engineers who are involved with the production, test, and development of RF components, circuits, sub-systems, and systems. Engineering degree and the course, RF Design - Core Concepts (#247), or equivalent background, including Smith chart and concepts such as wavelength, electrical length, and dB notation, are recommended.

Outline

Impedance Matching Techniques

 • Transmission zeros, LC network order • Maximum power transfer from Z1 to Z2 • Single LC-section impedance matching • Bandwidth and parasitic considerations • Wideband match -- low circuit-Q • Narrowband match -- high circuit-Q • Illustrative examples

Lumped RF Component Models

 • Resistors • Inductors • Inductance and Q Variations • Capacitors • Effective Capacitance and Q Variations • Primary self-resonance variations • Definitions of Magnetic Properties • Magnetic Core Applications • Ferrite Bead Impedance

Transmission Lines and Ground Parasitics

 • Via-Hole and Wrap-Around Ground Inductance • Parasitic Inductance and Capacitance Effects at RF • Multilayer PC-Board Parasitics • PCB/Interconnects • Open Stub Effects in Differential Vias • PC Board Materials • Transmission Line Realizations • Transmission Line Discontinuities • Converting an Electrical Circuit to Physical Form

Filters and Resonant Circuits

 • Introduction • Recipes for lumped-element filters • Parasitic loss and Q factor • Impedance inverters • Band pass filters with resonant structures • Piezoelectric filters • Filter element transformations

Active Circuit Fundamentals

 • Linear circuit definition • Amplifier Performance Limitations • Thermal Noise Definition • Harmonic Distortion Definitions • Gain Compression • Intermodulation Distortion • Spurious-Free Dynamic Range • Error Vector Magnitude • Various Power Gain Definitions • Testing for RF Stability • Causes of RF Oscillation • Typical Stability Circles for an RF Transistor • RF Stabilization Techniques • Nyquist Stability Analysis

Small Signal Amplifier Design

 • Transducer Gain Expression • Simultaneous Conjugate Match for Maximum Gain • Two-stage Amplifier Design for Gmax • Gain Definition - Block Diagram • Operating Gain Definitions • Operating Gain Circle Application • Maximizing Output Power • Available Gain Definitions • Available Gain Circles

Low Noise Amplifier Design

 • Sources of RF noise • Noise Factor and Noise Figure definitions • Noise of cascaded stages • Two-port noise parameters • Low-noise design procedure

Broadband Amplifiers

 • Broadband Concepts • Wideband Amplifier Design Overview • Gain Control and Impedance Matching in Feedback Amplifiers • Series and Parallel Feedback Applications • 10-4000 MHz Feedback Amplifier Design • Equivalent Circuit for Microwave FET • Distributed Amplifier and Cascode Connection

Nonlinear Circuits & Concepts

 • Where nonlinearity is important • Methods for nonlinear analysis • X Parameters

High Efficiency Power Amplifier Design

 • PA transistors • Matching for maximum gain or output power • Load-pull measurement techniques • Predicting output power contours • High efficiency techniques • Class A, B, C, D, F, harmonic termination consideration

Receivers and Their Architecture

 • Noise floor, maximum input, and dynamic range • Receiver spurs • Block diagram • Channel selection • Filtering • Downconverters / Mixers • Effects of phase noise • Quadrature demodulation

Modulation Techniques

 • AM, FM, digital • Multiple access • Bit error rate and SNR • CDMA • MIMO • Baseband filtering • Effects of distortion

Frequency synthesis, PLL design

 • Basic PLL and closed-loop response • Loop filters • Frequency dividers • Output spectrum • Contributors to phase noise

Feedback and negative resistance oscillator design

 • RF stability and loop gain • Feedback oscillators and open-loop design • Reflection oscillators

AM FM Noise Considerations

 • AM and FM decomposition of noise • Physical origins of noise • Noise conversion in amplifiers and oscillators

VCOs, DROs and crystal oscillators

 • Electronic tuning strategies • Oscillator specification, testing • Commercially available VCO’s