Calibration Theory - Measurement Computing PCI-DAS64/M1/16 User Manual

PCI-DAS64/M1/16 User's Guide
Calibration Frequency (kHz)
2
15
50
100
300
650
For best results, calibrate the board immediately prior to making your measurements. The high-resolution
analog components on the board are somewhat sensitive to temperature and this pre-measurement calibration
helps assure your board operates at the same temperature at which it was calibrated.

Calibration theory

Offset calibration for the analog front end is performed via adjustments of the ADC itself. Front-end gain
adjustment is performed only via the ADC reference. This strategy was chosen since the gain tolerance of the
in-amp circuit is quite good and there is adequate gain tuning range using only the ADC.
Analog input calibration is shown in
Calibration
Reference
Table 5-1. A/D calibration frequencies
Min Sampling Frequency (kHz)
0.01
6
30
70
200
400
Figure 5-2 .
Analog In
MUX
Trim DAC
Coarse
Trim DAC
Fine
Trim DAC
Coarse
Trim DAC
Fine
Figure 5-2. Analog front-end calibration system
5-2
Calibrating the PCI-DAS64/M1/16
Max Sampling Frequency (kHz)
6
30
70
200
400
1000
ADC
Offset Gain
Adjust
Adjust