Agilent Technologies 4339B Service Manual

Ammeter
Section
The
ammeter section
converts
current
owing
into
to
corresponding
digital
data.
The
section
includes
an I-V
converter
,
reference
current
source
,
and
the
Analog-to-Digital
Converter
.
I-V
Converter.
Figure
4-5
shows
the
I-V
converter
block
diagram.
Figure
4-5.
I-V
Converter
Block
Diagram
The
I-V
Converter
is essentially
an integrator
composed of
an operational
amplier
and
a
capacitor
.When
current
Ix
ows
into
the
integrator
,
the
current
charges
capacitor
C.
As
a
result,
the integrator
outputs a
negative
going
ramp
of
which
slope
is
0
I
x
C
.
The current
Ix
can
be
obtained
by
0
C
1
v
1
t
,
where
1t
is
a
certain
time
interval, and
1v
is
the
output
voltage
drop for this interval. Capacitor C, which is called range
capacitor, determines the applicable
measurement range in a practical integrator
.
Reference Current Source
. The Reference Current Source is an internal current reference
,
which provides the I-V converter with some sets of pre-dened dc currents
. The source is used
for the power-on self test sequence and for the calibration function.
Troubleshooting 4-7

Agilent Technologies 4339B Specifications

General

Brand	Agilent Technologies
Model	4339B
Category	Measuring Instruments
Language	English