Английски език
This new edition covers the theory and design techniques of the major types of radio-frequency power amplifiers (also named resonant DC-to-AC power inverters). Included are descriptions of Class A, B, AB, C, D, E, DE, and F RF power amplifiers which are used primarily in radio transmitters. The second edition has been completely revised and updated for a new generation of students and design engineers. Some examples are replaced by new and better examples, with many more added. Some end-of-chapter problems are replaced by new problems, and more have been added. More rigorous treatment of many concepts is seen in all chapters (plus all typographical errors have been corrected since the first edition). Chapter 1: Introduction containsmore in-depth coverage of radio communication systems, statistics of transmitter output power level and long-term average transmitter efficiency, and transmitter noise. Many students who take related classes based on the book do not have sufficient background in communications systems, and this updated chapter will help them in their studies. Two brand chapters have been added - the first -Chapter 11 - describes RF power amplifiers with dynamic power supplies. It details the improvement of the efficiency of nearly linear RF power amplifiers (Class A and AB) by the application of a variable supply voltage of RF power amplifiers, as opposed to fixed voltage power supplies, where a variable envelope signals are amplified, such as AM signals. This chapter also covers the applications of variable voltage supply as an AM modulator for RF power amplifiers, where the transistors are operated as switches. The second brand new chapter (Chapter 12) describes RF LC oscillators; an integral part of RF transmitters and also RF receivers. Chapter 8 (Class F RF Power Amplifiers) has been completely revised to cover the latest research results in this area. Old examples are replaced by new examples based on the new equations. Chapter 9 (Linearization and Efficiency Improvements of RF Power Amplifiers) has been extended to include new research results. In the author's experience, some students who take classes based on the first edition do not have sufficient background in electronics. To resolve this, he has added descriptions of operation of transistors as dependent-current sources and as switches. The author has added coverage of transistor current and voltage stresses, and information on the long-term average efficiency of RF transmitters.
