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Analysis and design of a limit-cycle amplifier taking into account the propagation delay of the relay

Duarte, M. J. D. ; Cabral, P. M. ; Pedro, J. C.

Analysis and design of a limit-cycle amplifier taking into account the propagation delay of the relay, Proc Conf. on Telecommunications - ConfTele, Castelo Branco, Portugal, Vol. 1, pp. 85 - 88, May, 2013.

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Abstract
Limit-cycle, sliding-mode or self-oscillating power
amplifiers (SOPAs) are seen as a simple architecture to efficiently
amplify signals with little distortion. Although originally designed
for audio applications, they are currently being employed
in wireless telecommunications, namely as envelope amplifiers
for envelope-tracking and envelope elimination and restoration
schemes. Usually employing high-order filters to guarantee instability
and ease their analysis, the work reported in this
paper takes advantage of the inherent propagation delay of the
switching stage to allow oscillation without the use of hysteresis
for low-order systems. For that, the analysis and design of a
limit-cycle amplifier taking into account such propagation delay
is shown, and a working prototype is built.