A switching amplifier for capacitive loads using incremental resonant charging

A lightweight, compact, 61-channel linear switching amplifier system has been developed for aircraft use. Each channel accepts input in the +10V range and outputs +1500V. into a capacitive load of 0.05 μf. The design employs a system of predictive incremental resonant charging (PIRC) of the load, controlled by a system clock. Central to the concept of PIRC is a means of calculating switching time for hot-switching transistors. Internal losses are minimized to hold size and weight to a minimum. The amplifiers as designed are flat in frequency response from dc to 4 kHz, and to 400 Hz without slew rate limitation. The system is intended to drive piezoelectric actuators of an adaptive optics mirror system, but the concept is applicable to any capacitive load. An overall design of the system was completed, and a two-channel breadboard was constructed, debugged, and tested. The tests showed that the system design requirements were met with only minor deficiencies.