Energy Saving Techniques for Industrial Linear Power Amplifiers

In industrial applications such as modern piezoelectric inkjet printers or automated device testers, arbitrary voltage waveforms need to be reproduced onto different type of loads, with an excellent linearity, preserving high signal to noise ratio with acceptable stability margin and high EMI immunity. These stringent requirements can be easily achieved if linear power amplifiers (LPA) are employed. Nevertheless, their power density is limited by the large heat-sinks due to dissipative behavior of the Class A/AB/B output stage. In this paper we present an overview of two energy saving techniques that significantly improve the performance of LPAs. The first technique is applicable in cases with very fast output voltage dynamics (slew-rates up to 45V/mus), while the second design provides an optimized, very compact solution in the case when alleviated requirements regarding the output voltage dynamics (slew-rates up to 2V/mus) have to be met.