Specifications

5
Each DC power module in the Agilent
N6705 DC power analyzer has a
fully integrated digitizer to capture
the actual voltage-versus-time and
current-versus-time being sourced
from the DC output into the DUT. The
digitized data appears on the large
color display just like an oscilloscope.
Because this oscilloscope function is
built in, it is possible to make current
measurements without current sense
resistors, current shunts, or current
probes. This greatly reduces measure-
ment setup complexity and provides
for accurate and fully specified, cali-
brated measurements. The accuracy
of the measurements in oscilloscope
mode is based on the type of power
module installed (basic, high-perfor-
mance autoranging, precision, and
SMU). You can find this information
in the Agilent N6700 Modular Power
System Family Specifications Guide
under “Oscilloscope Measurement
Accuracy.”*
The N6760 and N6780 SMU series of
power modules offer simultaneous
digitizing of output voltage and output
current, such that you can view a
voltage trace and a current trace at
the same time on the oscilloscope
display. For all other module types,
you can select to view either a volt-
age trace or a current trace on the
oscilloscope display.
Oscilloscope: Scope View
The table below shows the relation-
ship between the number of scope
traces, the sample rate, and the
buffer size available for each trace.
As shown, the digitizer can run at up
to 200 kHz with up to 256 k samples
per trace (512 k samples with SCPI
commands). With an effective mea-
surement bandwidth of up to 30 kHz,
this oscilloscope function is perfectly
matched to capture time varying
events on the DC output, such as
peak current demand, dropouts, rise
times and other DC transients and
disturbances.
The measurement buffer size can be
set to between 1 k and 256 k points.
Whatever buffer size is selected,
its available points must be divided
by the total number of traces being
measured.
Figure 5. In scope view, voltage and
current traces are displayed. In this picture,
the DC current fl owing into the DUT is
clearly visible as a time-varying waveform.
Power module type Number of traces
(1 trace = V or I)
Fastest sample rate Maximum buffer
size available per
trace
One N6780 SMU 1 trace 5.12 µs
(~ 200 kHz)
256 k points
Any power module 1 or 2 traces 10.24 µs
(~ 100 kHz)
128 k points
Any power module 3 or 4 traces 20.48 µs
(~ 50 kHz)
64 k points
* Complete specifi cations are available at
http://cp.literature.agilent.com/
litweb/pdf/N6700-90001.pdf
Note that the measurement window
is determined by multiplying the
selected buffer size by the sample
rate. For a measurement window of
60 seconds for example, with a buffer
size set to 256 k points, the fastest
sample rate available to you will
be 234 microseconds. If the buffer
size is set to 64 k points, the fastest
available sample rate will be 937
microseconds.
The oscilloscope can be triggered
on either voltage or current levels.
Because the Agilent N6705 DC power
analyzer is an integrated instrument,
the oscilloscope can also be easily
configured to trigger on the start
of an arbitrary waveform or to trig-
ger when the DC power output is
enabled. For example, to make an
inrush current measurement on your
DUT, you can set the oscilloscope to
trigger on the DC output’s on/off key,
set the trigger mode to single shot,
and then turn on the DC output. This
will immediately capture the current
flowing out of the DC module into the
DUT and give a picture of the inrush
current of the DUT. This integrated
functionality is not available when
using a collection of separate test
instruments on the test bench and
is an example of how the DC power
analyzer reduces setup time and
complexity.