HP-Bench-Briefs-1987-10-12.pdf | | SERVICE INFORMATION FROM HEWLETT-PACKARD
4th Quarter 1987
When a number is expressed in bi- REF
nary or binary-coded decimal and an
analog voltage is to be produced to
represent the number, the most prac-
tical way to perform this conversion
is to add the currents having values
proportional to the weights of the
G
binary bits. Figure 1 represents a
simplified binary weighted D/A con-
verter. Switches S1 to SN represent
the binary bits and connect either to
ground or a reference voltage. Figure
1 shows switch S1 connecting R to
the reference voltage and all other
switches connected to ground; but
since point A is a virtual ground,
there is no current through 2R, 4R,
up to 2N-1R. The amplifier has,
therefore, a gain of = -0.5 If |