The generation of RF/microwave power is required not only in wireless communications, but also in applications such as jamming, imaging, RF heating, and miniature dc/dc converters. Each application has its own unique requirements for frequency, bandwidth, load, power, efficiency, linearity, and cost. RF power is generated by a wide variety of techniques, implementations, and active devices. Power amplifiers are incorporated into transmitters in a similarly wide variety of architectures, including linear, Kahn, envelope tracking, outphasing, and Doherty. Linearity can be improved through techniques such as feedback, feedforward, and predistortion.

Absfracr-The class E tuned power amplifier consists of a load network and a single transistor that is operated as a switch at tbe carrier frequency of tbe output signal. 'zbe most simple type of load network consists of a capacitor shunting tbe transistor and a series-tuned output circuit, which may bave a residual reactance. Circuit operation is determined by tbe transistor when it is on, and by the transient response of the load network when tbe transistor is off. The basic equations governing amplifier operation are derived using Fourier series techniques and a high-Q assumption. These equations are then used to determine component values for optimum operation at an efficiency of 100 percent. Other combinations of component values and duty cycles which result in lOO-percent efficiency are also determined. 'fbe barmouic structure of tbe collector voltage waveform is analyzed and related amplifier configurations are discussed. While tbis analysis is directed toward the design of bigbefficiency power amplifiers, it also provides insight into tbe operation of modern solid-state VHF-UHF tuned power amplifiers.

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The predicted average efficiency of the asymmetric class-E outphasing is 98.7% for a signal with an SRRC (pi/4-QPSK) envelope (3.8-dB peak to average ratio) and 88.7% for a Rayleigh-signal with a 10-dB peak to average ratio. In contrast, the average efficiencies for an ideal linear class-B PA are only 51.8 and 28%, respectively.Class-E operation at UHF and microwave frequencies can be approximated by using transmission-line networks to control a finite number of harmonics [9][10][11]. The T networks used in the 1.8-MHz prototype are replaced by transmission lines. Work is underway on a two-harmonic class-E PA that produces 10 W with 71% efficiency at 900 MHz.ABSTRACT: Parallel implementation of the multilevel characteristic basis function method is discussed in this article. The use of this method enables us to solve very large electromagnetic problems in a direct manner via a recursive application of the characteristic basis function method. Furthermore, we show that, unlike the iterative schemes, the present method is very well suited for parallelization. Examples are presented to show that upto one million unknown problems can be solved on a workstation using the present scheme, and that the results show very good agreement with those derived by using analytical or fast multipole methods.ABSTRACT: We propose a network of bidirectional, wireless data channels, operating in the frequency band of 55-65 GHz, as an efficient means to transfer data between processors and memory nodes distributed on separate boards within the computer box. We address channel throughput, power dissipation, form factor, and crosstalk abatement.