A Comparative Study on Class AB and Class D Amplifier Topologies for High Temperature Power Line Communication Circuits

Power line communication (PLC) is widely used in the well intervention industry to control tools performing maintenance on oil and gas well pipes. This paper compares PLC driver power amplifiers and the impact of temperature towards them. As both a Class AB and Class D amplifier stages form suitable candidates, a comparison is made on performance indicators, such as total harmonic distortion (THD) and intermodulation distortion (IMD), as well as power limitations and efficiency. Measurements are performed both at room temperature and at high temperature of 150 °C. The trade-off between Class AB and Class D based on the mentioned indicators is then further emphasized using plotted responses. These show a clear advantage in the use of a Class D amplifier topology based on efficiency by outperforming the Class AB topology by a factor of two at high temperature. However the THD is found to be approx. 25dB better in the Class AB amplifier. This article discusses and thereby identifies future research trends and topics required for high temperature PLC driving circuits.