ENGINEERING TRIPOS PART IIA – 2012/2013

Module 3B1 – Radio Frequency Electronics

AIMS

Modern communication products such as radios, mobile ‘phones and GPS receivers utilise circuitry which operates at very high frequencies.  This course aims to give an introduction to circuit architecture, operation and design techniques used for signals ranging from the audio range up to microwave frequencies ie. kHz – GHz.  Also included is some material on antenna operation and design, a key part of radio systems.

SYLLABUS

• Transistor characteristics and circuit design: JFET, MOSFET and Bipolar devices.  High frequency performance and the Miller Effect, input and output impedances.
• Multiple transistor circuits: cascaded amplifiers, current sources and differential amplifiers.
• Filters: operational amplifier VCVS filters, resonant circuits, gyrators, ceramic.
• Oscillators: relaxation, Wein Bridge, resonant – negative impedance, Colpitts, quartz crystal, voltage controlled oscillators, phase locked loop.
• Impedance matching: LC circuits, transformers, transmission line.
• Radio architecture: ‘crystal set’, Superhet, digital radio.
• Mixer circuits: simple diode, Gilbert cell, diode ring, dual gate MOSFET.
• Modulation and demodulation schemes: AM, FM, PSK, FSK and circuits: F®V, V®F, diodes, multipliers, PLL.
• Microwave circuit techniques: microstrip and stripline, characteristic impedance, s & z parameters, Smith chart.
• Antenna principles and design: dipole, microstrip patch, helical, array antennas.

OBJECTIVES

On completion of the course students should be able to:-

• Understand the various characteristics of transistors including high frequency effects and circuit techniques which exploit them.
• Explain the Miller effect and how it influences the frequency response.
• Design basic multiple transistor circuits and to calculate their output and input impedances.
• Know the disadvantages and advantages of positive feedback.
• Explain how to make single and variable frequency oscillators.
• Design simple RF impedance matching circuits including the use of Smith charts.
• Understand the architecture and circuits used in radio applications and be able to design simple functional blocks.
• Know the basic theory and design principles of microstrip, stripline and antenna structures.

ASSESSMENT

Lab Experiment

The module is accompanied by the lab experiment: ‘Superhet radio’ situated in the Electrical and Information Engineering Teaching Laboratory (EIETL).

REFERENCES

Please see the Booklist for Part IIA Courses for references for this module.