Performance of a Diode-Clamped Linear Amplifier

This paper proposes a new high-efficiency diode-clamped linear amplifier, and presents its theoretical and experimental performance. The main circuit of the proposed amplifier consists of series-connected MOSFETs, series-connected dc power supplies and clamping diodes. The circuit configuration is similar to a diode-clamped multi-level inverter, except for using complementary power semiconductor devices, n-channel and p-channel MOSFETs. A pair of complementary MOSFETs in each leg is operated in an active state, just like a conventional linear amplifier, whereas the other MOSFETs are operated in either on- or off-state like a diode-clamped multilevel inverter. As a results, a prototype 12-series diode-clamped amplifier shows an experimental efficiency as high as 90%, while a conventional linear amplifier has a theoretical efficiency of 78.5%. Experimental results demonstrate that the proposed amplifier has the capability of driving a three-phase induction motor rated at 2.2 kW.