Active Clamped Half-Bridge CDR Converter for 48 V Data Center Voltage Regulator Modules

In 48 V data center voltage regulator modules (VRMs), current doubler rectifier (CDR) converter is favorable due to its high step-down ratio and structural simplicity. However, CDR converters suffer from excessive voltage stress on primary components caused by high switch turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> currents. This work addresses this limitation through an active clamp technique. The proposed design achieves zero-current switching (ZCS) in primary switches, eliminates voltage spikes, and maintains stability across a 40–60 V input range. Experimental validation via a 48 / 1.8 V, 500 kHz prototype demonstrates 92.24% peak efficiency while confirming: 1) ZCS operation in primary switches; 2) suppression of body-diode freewheeling; 3) elimination of duty-cycle loss; and 4) robust voltage regulation under wide input variations.