NI 5442
DC Offset
The NI 5442 supports a DC offset before the attenuation chain that affects the maximum value of DC offset for a given gain setting. This preattenuation architecture requires two rules for setting the DC offset:
- The magnitude of the maximum value of offset can be no more than ½ of the configured gain setting for the NI 5442.
- The waveform maximum plus the offset must not exceed ±1 V into 50 Ω; if it does, the waveform is clipped.
For example, if you have set a gain of .75, which corresponds to an amplitude of .75 Vpk, and the waveform is a sine wave using the full range of the DAC, the maximum DC offset you can apply without clipping the sine wave is ±.25 V. At this point, output voltages of the sine waveform have reached the maximum amplitude that the device supports. If you increase the DC offset further, the top portion of the waveform at 1 V is clipped.
NI-FGEN automatically calculates the preattenuation offset value based on the set DC offset and gain values. You can change the DC offset at any time during waveform generation. Refer to the Arbitrary Waveform Offset property or the NIFGEN_ATTR_ARB_OFFSET attribute for more information about setting the DC offset.
You cannot set the DC offset if you selected the Direct path. However, the output signal still has some non zero offset. Refer to the NI 5442 specifications for information about the maximum value of the DC offset.