Charge transfer device having a subdivided channel output region

Claim 1

A charge transfer device, which comprises: a semiconductor body having a major surface and a charge transfer channel; a row of clock electrodes on said major surface of the semiconductor body and over said charge transfer channel; a reading stage for detecting transferred charge packets; means for supplying clock voltages to said row of clock electrodes during a clock period to transport information-representing charge pockets through said charge transfer channel to said reading stage; said charge transfer channel being subdivided into at least first and second adjacent subchannels at the area of the reading stage, said subchannels comprising separate first gates, a common second gate and a separate third gate, charge packets being alternately introduced into said subchannels during operation by said separate first gates, said common second gate being capable of being held at an electrically floating potential during operation and providing an output signal representative of the size of the charge packet stored beneath said second gate, and said charge packet stored beneath said second gate being further transported by said third gates; means for biasing said second gate at said floating potential during reading of a charge packet stored under said second gate in the first subchannel and subsequently reading a charge packet stored under said second gate in the second subchannel, so that output signals can be derived from said reading stage over substantially the whole clock period which are substantially constant over substantially the whole clock period and representative of the information to be read; means for applying clock voltages to said first gates in phase opposition and for applying clock voltages to said third gates in phase opposition; and a further gate above each of the subchannels and between the first gates and the second gate, the first gate and the third gate being conductively connected together above each subchannel.