Exploring figures of merit associated with the suboptimum operation of class-E power amplifiers

Closed-form design equations for the operation of a class-E amplifier for zero switch voltage slope and arbitrary duty cycle are derived. This approach allows an additional degree of freedom in the design of class-E amplifiers which are normally designed for 50 duty ratio. The analysis developed permits the selection of non-unique solutions where amplifier efficiency is theoretically 100 but power output capability is less than that the 50 duty ratio case would permit. To facilitate comparison between 50 (optimal) and non-50 (suboptimal) duty ratio cases, each important amplifier parameter is normalised to its corresponding optimum operation value. It is shown that by choosing a non-50 suboptimal solution, the operating frequency of a class-E amplifier can be extended. In addition, it is shown that by operating the amplifier in the suboptimal regime, other amplifier parameters, for example, transistor output capacitance or peak switch voltage, can be included along with the standard specification criteria of output power, DC supply voltage and operating frequency as additional input design specifications. Suboptimum class-E operation may have potential advantages for monolithic microwave integrated circuit realisation as lower inductance values (lower series resistance, higher self-resonance frequency, less area) may be required when compared with the results obtained for optimal class-E amplifier synthesis. The theoretical analysis conducted here was verified by harmonic balance simulation, with excellent agreement between both methods. © The Institution of Engineering and Technology 2007.

A carefully curated collection: female figures as sites of inscription in Gautier’s Émaux et Camées

This article examines the ways in which female figures function as additional sites for poetic inscription in Gautier's Émaux et Camées. Although considerable attention has already been paid to the numerous and varied objects catalogued in the collection and, indeed, to the notion of the poems themselves as objects, the present study aims to expand upon such interpretations of the work by focusing on three texts, "Le Poëme de la femme", "Étude de mains : Impéria" and "La fellah". In these poems, female figures who, while they may at first be granted some agency (and be represented going about the business of daily, if highly stylized, life), are finally immobilized within the verse as their bodies, and particularly their pristine skin, ultimately function as an additional paper-like surface for the poet, permitting their assimilation into Gautier's diminutive private collection.