Specifications

Performance Verification 2
Series N6700 Service Guide 15
CV Ripple and Noise
Test category = performance
Periodic and random deviations in the output combine to produce a
residual AC voltage superimposed on the DC output voltage. This
residual voltage is specified as the rms or peak-to-peak noise in the
frequency range specified in the Agilent N6700 Modular Power
System Family Specifications Guide.
1 Turn off the power system and connect a load resistor or
electronic load, differential amplifier, and an oscilloscope (ac
coupled) to the output (see Test Setup C)..
2 For models N6751A/52A, N6761A/62A, and N678xA SMU - use an
appropriate load resistor to keep the power system at the
instrument setting specified in the test record form under “CV
Ripple and Noise”. For all other power modules - use an electronic
load to keep the power system at the instrument setting specified
in the test record form under “CV Ripple and Noise”.
3 As shown in the diagram, use two BNC cables to connect the
differential amplifier to the + and − output terminals. Each cable
should be terminated by a 50 Ω resistor. The shields of the two
BNC cables should be connected together. Connect the output of
the differential amplifier to the oscilloscope with a 50 Ω
termination at the input of the oscilloscope.
4 Set the differential amplifier to multiply by ten, divide by one,
and 1 MΩ input resistance. The positive and negative inputs of
the differential amplifier should be set to AC coupling. Set the
oscilloscope’s time base to 5 ms/div, and the vertical scale to 10
mV/div. Turn the bandwidth limit on (usually 20 or 30 MHz), and
set the sampling mode to peak detect.
5 Program the power system to the settings indicated in the in the
test record form for the appropriate model under “CV Ripple and
Noise” and enable the output. Let the oscilloscope run for a few
seconds to generate enough measurement points. On the Agilent
Infiniium scope, the maximum peak-to-peak voltage
measurement is indicated at the bottom of the screen on the right
side. Divide this value by 10 to get the CV peak-to-peak noise
measurement. The result should not exceed the peak-to-peak
limits in the test record form for the appropriate model under
“CV Ripple and Noise, peak-to-peak”.
NOTE
If the measurement contains any question marks, clear the measurement and
try again. This means that some of the scope data received was questionable.
6 Disconnect the oscilloscope and connect an rms voltmeter in its
place. Do not disconnect the 50 ohm termination. Divide the
reading of the rms voltmeter by 10. The result should not exceed
the rms limits in the test record form for the appropriate model
under “CV Ripple and Noise, rms”.
7 For models N678xA SMU only. Repeat steps 2 through 6 for the 6
V range.