My interest in oscillators started many years ago when I was an undergraduate
student and one of the laboratory experiments was the design of a Colpitts oscillator.
It was amazing to see how a sinusoidal signal appeared when the power supply
was turned on. What an interesting way of controlling the motion of electrons in
the circuit! My fascination with oscillators has remained to this date and, hopefully,
this book will be a reflection of it.
Electronic oscillator theory and design is a topic that, in general, is barely
covered in undergraduate electronic courses. However, since oscillators are one of
the main components in many electronic circuits, engineers are usually required
to design them. Sinusoidal carrier signals are needed in transmitters and receivers,
and timing signals (square-wave signals) are needed in digital circuits.
The purpose of this book is to cover the foundations of oscillator circuit design
in a comprehensive manner. The book covers the theory and design of oscillators
in the frequency range that extends from the audio range to the microwave range
at about 30 GHz. In this large range of frequencies the active element is usually a
semiconductor, such as a BJT or FET, or an op amp. The techniques involved in
the design of oscillators at the lower frequencies are different from those used at
the higher frequencies. An important feature of this book is the wide and rather
complete coverage of oscillators, from the low-frequency oscillator to the more
complex oscillator found at radio frequencies (RF) and microwave (MW) frequencies.
This book emphasizes the use of simulation techniques (i.e.,CADtechniques) in
the design of oscillators. In many cases the performance observed in the simulation is
very similar to that obtained in the laboratory. This is mostly true for oscillators
working at the lower frequencies and up to a few megahertz. As the frequency
increases, the practical implementation is highly affected by the layout and by the
parasitics associated with the components used. In such cases the simulation should
provide a starting point to the associated practical implementation.
The advances in CAD techniques since the 1980s have certainly changed the
approach to the design of many oscillators. Before the advent of advanced CAD
techniques, oscillator design involved a significant amount of theoretical work,
especially for those oscillators operating in the RF and MW-frequency regions.
While a solid theoretical foundation is still needed, the modern CAD programs
can perform a lot of nonlinear simulations that were once only a dream in oscillator
analysis and design. In my experience the best oscillator designers are those who
have a good understanding of the fundamental principles involved, experience with
an appropriate CAD program, and a good practical sense.