This reference design is a negative-to-positive synchronous buck-boost converter for power amplifier applications. The circuit is powered from the nominal -48-V system source to provide an output voltage of +48 V at 25 A. The design uses two dual synchronous boost controllers for 4-phase operation at a switching frequency of 150 kHz. Output voltage adjustment to +30 V is jumper selectable. 1- through 4-phase operation is also jumper selectable.