Chapter 5
Signal Generation Fundamentals
NI PXIe-5450 User Manual
5-6
ni.com
bandwidth of the output signal to meet the sampling criteria (Shannon's
Sampling theorem).
DAC Resolution
Digital-to-analog converter (DAC) resolution is a limiting factor in
determining the accuracy of the re–creation of an analog waveform from
digital samples. More details are present in the waveform if the DAC
resolution is increased. A 3-bit DAC divides its vertical range into eight
discrete levels. With a vertical range of 10 V, the 3-bit DAC cannot
generate voltage differences smaller than 1.25 V. In comparison, a 16-bit
DAC with 65,536 discrete levels can generate voltage differences as small
as 153 µV.
The following figure shows the difference between two waveforms. The
16-bit waveform looks like a continuous sine wave, but if you were to zoom
in, you would see the discrete steps of 153 µV. Both waveforms are
composed of discrete voltage steps, but the 16-bit version looks much
closer to a “pure” continuous-time sine waveform.
Amplitude (V)
0
50
000
001
010
011
100
101
110
111
100
150
200
10.00
8
.75
7.50
6.25
5.00
3
.75
2.50
1.25
0
Time (
μ
s)
3
-Bit
16-Bit
