The underlying concept of the invention disclosed is the use of charge partitioning for providing a precision weighted tap in a bucket brigade circuit. At the drain node of a charge conducting element in a bucket brigade device, the signal path is split in half with a first half going to the source of a first FET and the second half going to the source of a second FET. The first and second FET devices have their associated overlap capacitances, transconductances and threshold voltages matched by virtue of their close proximity to one another on the semiconductor substrate so as to have matched charge transfer characteristics. The amplitude of the charge stored on the capacitor at the node is therefore divided into two parts, with one portion being transferred by the first FET device and the remaining portion being transferred by the second FET device. This simple circuit accomplishes a precise charge division for the charge entered into the bucket brigade circuit. Successive cells in the bucket brigade device can have their drain nodes connected to matched pairs of first and second FET devices to successively divide the charge stored therein by one-half so that a sequence of decrements in the charge transferred along the bucket brigade chain may be made in multiples of one-half. By selectively gating the outputs of each of the respective tapped branches from the bucket brigade device at a summing node, values of from zero to unity in fractional unit intervals can be generated as an analog output. A digital to analog converter may be formed by inputting a serialized digital word into the input of the bucket brigade device whose successive cells have attached thereto respective pairs of FET charge partitioning devices. The outputs of all branches are summed so that a resultant charge, which is the sum of the charges output by the charge partitioning transistors, will appear at the output as the analog value for the binary serial word input to the bucket brigade device.
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