This work presents a rigorous electrical analysis of charge-pump conditioning circuits for capacitive energy converters (CEG) with built-in bias voltage. The subsequent implications on the selection of the optimal conditioning circuit are also presented. In particular, the determining role of the application context and constraints on the optimal conditioning circuit choice is discussed. This context is defined by the transducer's capacitance variation amplitude, by the value of the built-in bias of the transducer, and by limitations on the operating voltages across the circuit elements and the transducer.