Agilent Technologies E4438C - Manual (Page 124)

Adjustments
ALC Calibration
4-32
ALC Calibration
Description
This calibration is used to ensure zero offset and linear performance of the ALC Reference DAC. This is done
by adjusting four different “control DACs”. The Log Offset DAC is adjusted first to center the ALC loop
around a reference-setting of 2048. Next, the Detector Offset DAC and Bulk R Adj DAC are iteratively
adjusted to achieve linearity over the entire ALC range. Finally, the Ref Gain DAC is adjusted to achieve a
final ALC slope (nominally 50 DAC counts/dB at a single frequency).
Figure 4-24 ALC Calibration