Chapter 2
NI 5450 Overview
NI PXIe-5450 User Manual
2-14
ni.com
Analog Output
The following figure shows the NI 5450 Analog Output signal path.
NI 5450 analog waveforms are generated as follows:
1.
The 16-bit digital waveform data from the Waveform Generation
Engine or OSP is passed to a digital gain circuit and then high-speed
DAC. This DAC also implements a portion of the Analog Output
signal path attenuation with a range of 0 to 3 dB. Refer to the NI 5450
specifications for the exact resolution. You can adjust the amount of
attenuation by configuring the Arbitrary Waveform Gain property or
the
NIFGEN_ATTR_ARB_GAIN
attribute. NI-FGEN calculates and sets
the correct amount of attenuation required, corresponding to the gain
setting.
2.
Following the DAC, the signal follows the Direct path. The Direct path
can provide a maximum of 1.0 V
pk-pk
differential output into 50
Ω
with
a maximum of 3 dB attenuation.
3.
The signal then passes through the Output Enable relay. When the
Output Enable relay is disabled, ground is connected to the output
through a 50
Ω
resistor. Intentionally, waveform generation continues
while the output enable relay is disabled. When the relay is enabled,
the analog waveform is seen at the CH 0 +/
−
connector. Enable or
disable the output of the analog waveform generator by using the
16
DAC
Gain DAC
(0 dB to –3 dB)
Output
Enable
50
Ω
CH 0 +
from Waveform
Generation Engine
or
Onboard Signal Processing
Block
Output Enable
Relay
Digital
Gain
Output
Enable
50
Ω
CH 0 -
Output Enable
Relay
Direct
Path
Direct
Path
Lowpass
Filter
Lowpass
Filter
