Signal Processing for Burst‐Mode RF Transmitter Architectures

PhD Student 

Conventional RF power amplifiers (PAs) employed in transmitter architectures for wireless
communication systems are designed to be highly linear in order to fulfill spectrum emission and
linearity requirements imposed by modern telecommunication standards. However, linear amplifier
operation is usually inefficient and results in unnecessary power consumption. A promising approach
towards higher power efficiency is the concept of burst‐mode RF transmitters, where the idea is to
operate a PA in only two states: “on”, where the PA is driven into saturation with maximum
efficiency, and “off”, where no power is consumed or wasted at all. Hence, for the burst‐mode RF
transmitter concept, the PA is operated with a constant‐envelope signal. Since future
telecommunication standards like LTE utilize spectrally efficient non‐constant envelope modulation
schemes like QAM in combination with OFDM, which require high linearity, the use of burst‐mode
transmitters requires, on the one hand techniques to transform amplitude information into a pulsed
signal, and on the other hand linearization schemes like digital predistortion to compensate for the
distortion induced by the nonlinear behavior of the PA.

The objective of this thesis is to develop and implement flexible signal processing algorithms for
energy efficient and linear pulsed transmitters for mobile terminals. This requires the development
of accurate system models for burst‐mode PAs, the optimization of RF modulator and pulse‐width
modulator, and the linearization of pulsed transmitters.

Pulsed Transmitter Architecture.
This thesis is supervised by Christian Vogel.