Charge packet refreshment in a charge transfer device is performed by comparing an input charge packet to be refreshed with a reference level to form a corresponding signal and reference potential barrier and by ejecting charge from beneath a ramp electrode between said signal and reference potential barriers over the lesser of the two barriers. The area of the ramp electrode may be sufficiently large to generate refreshed charge packet of amplified size to spill over one of the two potential barriers in reponse to an input charge packet.