Chapter 8
Analog to Digital Conversion
47
EAR99
Technology
Subject
to
Restrictions
Contained
on
the
Cover
Page.
8.2
Analog Gain
Controller gain, a configurable function of the preamplifier, changes the relationship
between the number of electrons acquired on the CCD and the Analog-to-Digital Units
(ADUs) generated. The level of gain is configured by the Analog Gain parameter on the
Analog to Digital Conversion expander.
Supported Analog Gain options are:
•
Low
This gain setting is best suited for binning applications, particularly when
high-level signals are being digitized. Although this setting may be used with
non-binned modes, the CCD single pixel well typically will not reach ADC
saturation when applying Low gain.
•
High.
Applications that consistently measure low-level signals should select this gain
setting since it requires fewer electrons to generate each ADU. Additionally, this
setting can reduce some sources of noise.
NOTE:
The Certificate of Performance included with Lansis
specifies the measured gain values for various Analog Gain
settings.
Actual electron counts required are also dependent upon
the configured readout rate.
Table 8-1: Typical Electron Counts vs. Analog Gain Setting
Low
High
5 e
-
/count
0.7 e
-
/count
