Solid-State Transformers are conventionally based on a multi-stage architecture, with an input and/or an output AC/DC converter (for interfacing with the AC grid and/or the load), and with an isolated DC/DC conversion stage (to provide insulation and voltage/current scaling). Alternatively, some single-stage SST circuits use AC/AC conversion modules and rely on bidirectional blocking devices, which however have limited commercial availability and face significant operational challenges. This letter explains the derivation, operating principle, and fundamental topologies of a new family of solidstate transformers, named Modularized Diode Rectifiers. Their architecture is derived from the integration, within basic diode rectifier circuits, of DC/DC converter modules, which are fed by unipolar pulsating voltages. Despite using only DC/DC modules, this family of circuits can achieve isolated AC/DC and/or AC/AC conversion, can provide power factor corrector features, and can be easily scaled for higher voltage and/or current ratings.