4.2 Cancelling the dark current of sensor
CA5350
4-3
4.2 Cancelling the dark current of sensor
It is equipped with current source for cancelling the dark current of sensor and for
removing the offset component of
CA5350
itself. If the dark current of sensor is
cancelled, gain of
CA5350
can be set to even larger value, and measurement sensitivity
can be improved.
CURRENT SUPPRESSION
is the variable current source connected to input terminal,
and its setting range covers up to ±800µA over 6 ranges. Each range has the setting
resolution of ±8000.
Table 4-1 Current suppression setting range and resolution
Current Suppression
Setting Range
Setting
Resolution
8nA range
-8.000nA ~ +8.000nA
0.001nA (1pA)
80nA range
-80.00nA ~ +80.00nA
0.01nA (10pA)
800nA range
-800.0nA ~ +800.0nA
0.1nA (100pA)
8µA range
-8.000µA ~ +8.000µA
0.001µA (1nA)
80µA range
-80.00µA ~ +80.00µA
0.01µA (10nA)
800µA range
-800.0µA ~ +800.0µA
0.1µA (100nA)
フィルタ部へ
-
+
I/V GAIN
ゼロチェック
切替より
8nA
-8.000 ～ +8.000V
設定分解能 0.001V
直流電圧源
80nA
800nA
8uA
80uA
800uA
1GΩ
100MΩ
10MΩ
1MΩ
100kΩ
10kΩ
OFF
Figure 4-2 Block diagram of current suppression
Note that using the
CURRENT SUPPRESSION
function will increase noise in the output
signal of
CA5350
. The bigger I/V gain or
CURRENT SUPPRESSION
value is, the higher
the probability of introducing noise will be.
CURRENT SUPPRESSION
settings include the
MANUAL
mode where range and current
value are set manually, and the
AUTO
mode where current value and range required for
making the output voltage of
CA5350
to 0V is selected automatically.
To filter
From Zero Check
switch
DC current source
Setting resolution
