A Factorized Power Architecture ("FPA") includes a power regulator providing controlled DC bus voltages distributed and converted to load voltages, at the load, using DC voltage transformation modules ("VTMs") having fixed transformation ratios. Optional feedback from the load improves regulation. A Sine Amplitude Converter ("SAC") VTM locks the conversion frequency to resonance of a resonant circuit including a transformer, uses complementary primary switches, balanced switching, and a high conversion duty cycle, and may use primary ZVS and secondary ZVS and ZCS, low Q, and a low profile core structure, and may exhibit greater than 400 Watts/cubic-inch power density and 95% efficiency. Common-source gate-control topologies efficiently drive switches higher than 1 MHz. Symmetrical power trains reduce common-mode noise. Modulated converter output resistance controls V_out, limits I_out, or improves current sharing. Gate drive circuitry recycles energy from the transformer magnetizing inductance. A DC-DC converter includes a non-isolated converter followed by a SAC.