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D/A Converter Errors and Parameters
20
0
Amplitude — dB
–20
–40
–60
–80
–100
–120
f 2 – f 1 2f 1 – f 2
2f 2 – f 1
f 1
f2
f 1 + f 2
–130
0 1 k 2 k 3 k 4 k 5 k 6 k 7 k 8 k
Frequency – Hz
9 k 10 k
Figure 14–12.
Intermodulation Distortion
14.5.2.6 Settling Time
The best method of combating intermodulation distortion is to make the buffer amplifier
system as linear as possible (beware of rail-to-rail op amps that may not be linear near
the voltage rails). Try to limit current through the internal feedback resistor in the DAC.
See Paragraph 14.7.1 on increasing the voltage rail for suggestions about reducing internal
feedback resistor power dissipation.
The settling time of a D/A converter is the time between the switching of the digital inputs
of the converter and the time when the output reaches its final value and remains within
a specified error band (Figure 14–13). Settling time is the reciprocal of the maximum D/A
conversion rate.
14-16