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Theory of Operation
Grounding and Power
Grounding and Power
Grounding
Each printed circuit board has a single ground plane. The ground planes on the A4 RF
board and A5 system board are connected via the common shields at multiple points. The
ground plane on the A3 front panel interface board is connected to the ground plane on the
A5 system board.
There are no separate grounds in the analyzer. There is no "star" ground point in the
analyzer.
Batt Neg and Ext DC neg are connected to the A5 system board ground plane.
The A2 LCD assembly has two separate grounding circuits: the LCD power and control
circuits and the backlight LED's.
• The LCD power and control circuits share a ground that is connected to the ground
plane on the A5 system board.
• The ground for the backlight LED's is connected to the ground plane on the A3 front
panel interface board.
Voltages and Power Supplies
The following power supplies exist within the analyzer:
• Digital 5 volts—generated from Unreg DC on the A3 front panel interface board,
controlled by the System Monitor on the A5 system board, and used on the A3, A4, and
A5 boards.
• Digital 3.3 volts—generated from Unreg DC on the A3 front panel interface board,
on/off functions controlled by the System Monitor on the A5 system board, and used on
the A2 LCD assembly and A3, A4, A5, and A6 boards.
• Analog supply voltages—seven separate voltages generated from Unreg DC on the A5
system board, on/off functions controlled by the System Monitor on the A5 system
board.
• LCD backlight voltage—generated on the A3 front panel interface board from the
digital 5 volt supply voltage.
• Power for the System Monitor circuit—3.3 volt circuit powered from Ext DC or Batt +,
whichever is greater. Used on A5 system board only.
• Unreg DC—from Ext DC or Batt +, 21 volts max.
• Ext DC—from external Power AC Adapter, nominal 15 volts, acceptable up to 19 volts.
• Batt + —from main battery, nominal 12 volts.
All voltages except Ext DC, Batt +, and the System Monitor power can be turned on/off
within the analyzer. Refer to
information.
5-14
"Power Management Circuitry" on page 5-9
RF Vector Network Analyzer
N9923AN
for more
Service Guide N9923-90005
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Table of Contents
Troubleshooting
