Agilent Technologies 4284A, Operation Manual

Page: 102 / 460

Automatic Lev el Control
Function
Description
The automatic lev el con trol ( alc) function regulates the actual test
lev el (v oltage across the DUT, or curren t through the DUT) to y our
desired lev el. So b y using this function, the test signal v oltage or
curren t lev el at the DUT can b e held constan t.
When the automatic lev el con trol function is used, the oscillator lev el
settings are limited as follo ws.
When Option 001 is not installed, or the high p o w er mo de is set to
OFF
V oltage Lev el: 10 mV
rms
to 1 V
rms
Curren t Lev el: 100 A
rms
to 10 mA
rms
When the high p o w er mo de is set to ON
V oltage Lev el: 10 mV
rms
to 10 V
rms
Curren t Lev el: 100 A
rms
to 100 mA
rms
Note
When the ALC function is active, if the oscillator lev el setting
exceeds the ab o v e limits, the ALC function is automatically set to
OFF and the setting v alue is en tered as a normal oscillator lev el.
Note
The automatic lev el con trol is ac hiev ed using feedbac k with the lev el
monitor function as sho wn in Figure 4-4 . The feedbac k op eration
p erforms a lev el measuremen t/OSC lev el adjustmen t 2 to 6 times
p er measuremen t. (The time required (n in the follo wing formula)
dep ends on the device b eing tested. The more non-linear the device
is, the greater the time required.) When the ALC function can't
regulate the lev el using 6 output lev el measuremen t/adjustment
cycles (when a device has non-linear c haracteristics, the ALC
function may stop b efore the 6 output lev el measuremen t/adjustment
cycles), the ALC function stops, and a w arning message ALC unable
to regulate is display ed, and sets the oscillator lev el to equal y our
setting v alue, op en-lo op, the output lev el will b e the same as when
ALC is set to OFF. The time required for the ALC function to
op erate is calculated using the follo wing formula.
(meas.time (SHOR T) + appro x. 115 msec.) 2 n
Where, n = 2 (min.)
n = 6 (max.)
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