Chapter 2
NI 5450 Overview
©
National Instruments Corporation
2-5
NI PXIe-5450 User Manual
amplitude by calling the Arbitrary Waveform Gain property or
NIFGEN_ATTR_ARB_GAIN
attribute.
Load Impedance Compensation
The NI 5450 has the ability to configure the output signal amplitude based
on a user-configured load impedance setting. This capability is desirable
when you use the NI 5450 with loads that are between 0
Ω
and a high
impedance. Refer to the device specifications for information about the
output impedance tolerance.
By default, NI-FGEN assumes that the load impedance is equal to the
output impedance. If they do not match, you can change the load
impedance value that NI-FGEN uses in its load impedance compensation
algorithm. NI-FGEN takes the load impedance into account when setting
the amplitude and provides the amplitude specified in the configured gain
setting, eliminating the need to use the voltage divider equation. NI-FGEN
compensates to give the desired peak-to-peak voltage amplitude or
arbitrary gain (relative to 1 V). You can configure the load impedance by
calling the Load Impedance property or
NIFGEN_ATTR_LOAD_IMPEDANCE
attribute.
Note
The voltage output levels are set in the software and are based upon a 50
Ω
load
termination (the default), or based on the user–specified load resistance.
For waveform output signal specifications, refer to the device
specifications.
CLK IN Connector
The CLK IN front panel connector can accept an external Reference clock,
external Sample clock, or external Sample clock timebase.
Caution
Do
not
change the external clocks while generating waveforms. Only modify the
frequency of the external clock
before
you start the waveform generation or
after
you stop
the waveform generation. NI cannot guarantee the quality of the generated signal if you
change the external clock during waveform generation.
External Reference Clock Input
The CLK IN connector can accept a Reference clock from an external
source and phase-lock the internal clock of the signal generator to this
external Reference clock. Refer to the device specifications for the
allowable Reference clock frequencies and signal characteristics.
