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Digital Electronics
smallest when D has the full-scale value. Figure 12.22 shows the noninverting type of programmable
integrator. The output in this case is given by
V o = D/CR 1
V in dt
(12.10)
12.7.4 Low-Frequency Function Generator
Figure 12.23 shows one possible circuit configuration of a D/A converter based low-frequency function
generator. There is no limit to the lowest frequency possible using this configuration. The upper limit
−
+
OUT-1
R FB
V ref
OUT-2
R 1
−
+
C
V in
Figure 12.22 Non-inverting programmable integrator.
−
+
OUT-1
R FB
V ref
OUT-2
V o
−
+
V in
D/A
Converter
Sign
ROM
Clock
Counter
Figure 12.23 Low-frequency function generator.