Digital-to-Analog Conversion
As is true with A/D converters, D/A converters
are most often ICs, and various types are used.
Only one type will be presented here.
Figure 13-32(a) shows the schematic for a
4-bit D/A converter. Each SPDT switch represents a binary input. When a switch is set toground, the binary input is LOW or 0; the other
switch position is HIGH or 1. As shown in
Fig. 13-32(a), the 4-bit input happens to be
at 10002. What will Vout be? Using standard
op-amp theory:
The resolution (smallest step size) of the
D/A converter circuit shown in Fig. 13-32(a)
can be found by solving for the output voltage
Vout Vref
RF
Rin
5 V
1 k
1 k 5 V
produced when the least significant bit (20
) is
high:
The largest input is 11112, which is equal to
1510, and the maximum output voltage can be
determined by:
Vout1max2 0.625 V 15 9.375 V
0