A dual mode, single ended to fully differential converter structure is incorporated into a fully differential sample and hold structure which can be coupled with an ADC as a front end for mixed mode applications. The structure incorporates additional switches which allow negative and positive charges to be sampled on both negative and positive sides of the structure. By inverting the sampled charge on one side, single ended to fully differential conversion is obtained. The structure can be implemented in a compact, generic block which performs single ended to fully differential conversions as well as sample and hold functions, without compromising speed and accuracy in either mode.