Showing papers by "Nathan O. Sokal published in 2003"

RF and Microwave Power Amplifier and Transmitter Technologies — Part 3

Abstract: The building blocks used in transmitters are not only power amplifiers, but a variety of other circuit elements including oscillators, mixers, low-level amplifiers, filters, matching networks, combiners, and circulators. The arrangement of building blocks is known as the architecture of a transmitter. The classic transmitter architecture is based upon linear PAs and power combiners. More recently, transmitters are being based upon a variety of different architectures including stage bypassing, Kahn, envelope tracking, outphasing, and Doherty. Many of these are actually fairly old techniques that have been recently made practical by the capabilities of DSP. 7a. LINEAR ARCHITECTURE

RF and Microwave Power Amplifier and Transmitter Technologies — Part 2

Abstract: Part 1 of this series introduced basic concepts, discussed the characteristics of signals to be amplified, and gave background information on RF power devices. Part 2 reviews the basic techniques, ratings, and implementation methods for power amplifiers operating at HF through microwave frequencies. 6a. BASIC TECHNIQUES FOR

RF and Microwave Power Amplifier and Transmitter Technologies — Part 4

Abstract: Linearization techniques are incorporated into power amplifiers and transmitters for the dual purposes of improving linearity and for allowing operation with less back-off and therefore higher efficiency. This article provides a summary of the three main families of techniques have been developed: Feedback, feedforward, and predistortion. 8a. FEEDBACK Feedback linearization can be applied either directly around the RF amplifier (RF feedback) or indirectly upon the modulation (envelope, phase, or I and Q components).