DAC1020_11 Datasheet, PDF (8/16 Pages) Texas Instruments – 10-Bit Binary Multiplying D/A Converter

Typical Applications (Continued)
 ^{VOUT e}
bV_REF
A1 A2 A3
aaa
248
J ^A10
1024
where V_REF can be an AC signal
 By connecting the DAC in the feedback loop of an opera-
tional amplifier a linear digitally control gain block can be
realized
 Note that with all digital inputs low the gain of the amplifier
is infinity that is the op amp will saturate In other words we
cannot divide the V_REF by zero
FIGURE 10 Analog-to-Digital Divider (or Digitally Gain Controlled Amplifier)
A1 A2
aa
24
V_OUT e V_{REF A1 A2}
%a a
24
A10
a
 J ¹⁰²⁴
1023 b N
A10 ^{or VOUT e VREF}
N
– a
1024
where 0 s N s 1023
N e 0 for A_N e all zeros
N e 1 for A10 e 1 A1–A9 e 0
N e 1023 for A_N e all 1’s
FIGURE 11 Digitally controlled Amplifier-Attenuator
7
TL H 5689 – 7
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