Charge transfer device equipped with charge signal detector improved in sensitivity as well as in voltage amplification

摘要

A charge coupled device transfers a charge packet to a floating diffusion region (16) for producing voltage variation therein, and the voltage variation is relayed to an output terminal (OUT) by means of a driving unit (17) implemented by a plurality of source follower circuits (17a/ 17b/ 17c) coupled in cascade, wherein each of the second to final source follower circuits (17b/ 17c) is implemented by a series combination of an enhancement type driving transistor (Q173/ Q175) and an enhancement type load transistor (Q174/ Q176), and the enhancement type load transistor changes the channel conductance thereof complementary to the enhancement type driving transistor under the control of a control unit (18) so as to improve the dynamic range of the output signal thereof without sacrifice of the sensitivity of the floating diffusion region.