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National Instruments Corporation
A-1
NI 54XX Calibration Procedure
A
Overview of the Calibration
Constants
This appendix provides an overview of the constants that you adjusting
for your device: low frequency characteristics of the analog channel, internal
reference, frequency response, duty cycle, and VCXO constants.
Low Frequency Characteristics of the Analog Channel
These constants represent the DC or low-frequency gains and offsets of
components within the analog channel. They are referred to as constants
A0 through A9 in the documentation and in the programming interface.
Unterminated refers to a high impedance load on the output of the device
and terminated refers to a 50
Ω
load. Constants A0 through A8 can be
calculated during an internal calibration. Constants A9_Unterminated,
A9_Terminated, and A9TA are calculated only during an external
calibration. Table A-1 shows the names of these constants and a brief
description of each.
Table A-1.
DC or Low-Frequency Gains and Offsets of Components within the Analog Channel
Constant
Name
Description
A0
Output dependence on the cumulative offsets of the gain calibration DAC and
main DAC.
A1
Output dependence on the gain of the offset calibration DAC.
A2
Output dependence on the gain of the gain calibration DAC.
A3
Output dependence on the offset of the gain calibration DAC and the gain of the
main DAC.
A4
Output dependence on the gains of the gain calibration DAC and the main DAC.
A5
Output dependence on the offset of the offset calibration DAC.
A6
Output dependence on the cumulative offsets of the amplifiers in the analog
channel.