resonant inverter is the generic name for a type of high frequency switching topology used in many of Spellman's supplies. Resonant switching topologies are the next generation of power conversion circuits, when compared to traditional pulse width modulation (PWM) topologies.

Resonant-based supplies are more efficient than their PWM counterparts. This is due to the zero current and/or zero voltage transistor switching that is inherent in a resonant supplies design. This feature also provides an additional benefit of eliminating undesirable electromagnetic radiation normally associated with switching supplies.