RF and Microwave Circuit Design: Applications and Theory

TECHNOLOGY FOCUS 
Although RF circuits are generally considered to be circuits that operate from tens of MHz up to 1GHz, and microwave circuits at frequencies beyond that, boundaries based purely on frequency are rarely appropriate. Analog integrated circuits based on lower-frequency design methodologies can now operate well into the microwave range, purely because of smaller feature sizes that are now available in CMOS and silicon-germanium technologies. BiCMOS integrated circuits that operate in the microwave frequency range, designed using low frequency architectures, are now abundant. 
However, classical microwave circuit design techniques are still important to model and understand problems arising from noise, mismatch, circuit losses, and limited bandwidth. We will focus on circuits that are differentiated from their historically lower-frequency counterparts by several features. In RF and microwave design, the phase shift of the component is significant because its size is comparable with a wavelength, its reactances and parasitics must be accounted for, and reflections occur between elements. We need to consider circuit losses that degrade the Q of an element as well as introduce noise, and nonlinearities that introduce distortion into the signal path. Electromagnetic radiation and capacitive coupling will also be features of such circuits. With integrated circuits, these 'RF and microwave' effects are most commonly observed when assembling circuits together at higher frequencies into systems, or when using discrete or custom devices.

COURSE CONTENT 
This course reflects modern trends. While focusing on the design of discrete RF and microwave circuits to show classical microwave design techniques, examples of integrated circuits are presented to compare the 'two worlds'.  As CMOS design now extends even beyond Ka-band frequencies, many of these classical microwave design insights and techniques are being lost. For instance, the use of a source inductor in a CMOS low-noise amplifier stage is widespread for simultaneously improving gain and noise match, but why?
Impedance matching, device modelling, circuit stability, power output, distortion, power combining, and component losses and parasitics are all examined, using state-of-the-art low-voltage transistors. This is illustrated in a number of applications such as small-signal, large-signal, low-noise, and feedback amplifiers with discrete transistors. Low-noise design considerations are also introduced, using CAD modelling of reactive and resistive types of applications. Reflecting its importance as a fundamental building block of most systems, amplifier design is treated exhaustively, using both small signal S-parameter methodologies (for noise, gain, and matching) and large signal models (for power and distortion).

Oscillators and mixers are also designed to meet demanding systems requirements. The course first explains the fundamental operating principles of these components in great simplicity, and then illustrates the theory elegantly through practice. We stress the importance of modeling parasitic elements that arise in design or when interconnecting components at high frequencies. We also consider oscillator and mixer performance using a system simulator, reviewing how these components need to be specified for use in communication systems, for instance to maintain I and Q channel orthogonality, and how this relates to the system performance. We will also look at higher level RF and microwave subsystems, such as LNBs and BUCs.

Nonlinear design techniques are also examined with a harmonic balance simulator, using bipolar, FET, and HEMT devices. The course emphasises hands-on design and simulation of many circuit types, considering their linearity, efficiency, and power requirements. We develop an intuitive understanding of how non-linearity arises, and its impact on design, together with more detailed circuit modelling to examine quantitative impact. 

To benefit most, bring your own laptop computer, and prior to attending the course, obtain a free trial license of Microwave Office (MWO) from AWR at  www.awrcorp.com .

Monday
Small-signal RF Circuit Design
To introduce linear active circuits, we start with the fundamental principles of impedance matching and move on to examine the effect of mismatch on performance.

• Revision of S-parameters, Matching and the Smith Chart
• Unilateral Gain Circles in Small-signal Amplifier Design
• Unilateral and Figure-of-Merit and Bilateral Design
• RF Circuit Stability: Graphical and analytical techniques
• K- and µ-Factors, Nyquist Stability Analysis

Example: Broadband Transistor Stabilization

• Stability of Cascaded Amplifiers
• Simultaneous Conjugate Match, Bandwidth Considerations
• GMAX and MSG Definition

Example: 1900MHz Amplifier Design for Maximum Gain 


Tuesday
Discrete Low-Noise and Broadband Amplifiers
We examine the three commonly used techniques used in maximum small-signal gain, low-noise, and linear power amplifiers.

• Transducer-, Operating-, and Available-Gain Techniques
• RF Noise Sources, Noise Figure and Noise Measure
• Constant-Noise and Constant-Gain Circles in LNA Design
• Available-Gain Design for Minimum Noise
• Trade-Offs Between Gain, Match, and Noise Performance

Example: 900MHz Discrete LNA Design

• Broadband Amplifier Design Techniques
• Reactive Mismatch and Lossy Matching Techniques
• Cascade Equalization
• Feedback Amplifiers Combined with Impedance Matching
• Circuit Optimization for Gain, Match and Stability
• Feedback Effects on Stability and Noise

Example: 1-4000 MHz Feedback Amplifier Design

Wednesday
Power Amplifier Design

• Design for Optimal Power
• Quasi-Linear Methods to Achieve Power Matching
• Load Line Characterization
• Load Pull Characterization - Measurement and Prediction
• Classes of Power Amplifiers: A, AB, B, C, and F
• Harmonic Tuning to Optimize Efficiency

Thursday
Power Amplifier Design (cont'd)

• Distortion Reduction Techniques

Example: Bipolar Power Amplifier Design Example (CDMA)

Low Noise (LC) Oscillators

• Oscillator Design Considerations
• Device - Circuit Interaction (Series and Shunt Resonances)
• Deriving the VCO Tuning Curve
• Phase Noise and Its Impact on System Performance
• Why a system engineer worries about phase noise

Friday
Low Noise (LC) Oscillators (cont'd)

Example: Bipolar Transistor (HBT) VCO Design in the 4 GHz Band

Mixer Design

• Revision of Diode Mixers
• Bipolar and MESFET Mixer Analysis
• Comparison of Mixer Types
• The Importance of Quadrature Balance
• Modulators,  Image-Reject, and Single Sideband Mixers

Example: FET and Bipolar Transistor Active Mixer Designs

Said about the course from previous participants:
"Broad knowledge of the teacher."
"Computer simulations to illustrate lecture topics."
"Very good mixture of theory, practical information and simulation."