Apparatus for converting data between digital and analog values

Abstract

Apparatus converts into an analog value signals representing digital values. Sub-sets of switches are provided, the number of switches in each sub-set being directly related to the digital significance of the switches in such sub-set. The switches in each sub-set may be paired to provide for a conductivity of one switch in each pair. The signals representing individual digital values are introduced to the associated sub-sets to provide for the conductivity of an individual one of the switches in each pair in accordance with the digital value represented by such signals. The switches are connected in a recursive relationship defined by repetitions of a basic block. Each basic block is in turn defined by a pair of basic sub-blocks. A plurality of capacitors are also provided as output members. The capacitors are connected to the recursive relationship of the switches to charge the capacitors through paths defined by the conductive ones of the switches. When the capacitors are conductive, the switches operate to introduce the charge from the capacitors to one of two output lines. For progressive increases in the digital value, a progressive number of the capacitors are connected to a particular one of the output lines, and capacitors previously connected to the particular output line are maintained connected to the output line with such progressive increases in the digital value. The cumulative current through the particular output line is indicative of the analog value.