Keysight Technologies N9030B Service Manual page 239

Analog/Digital IF Troubleshooting
A3 Digital IF Assembly Theory of Operation
Noise Source Voltage Regulator
DSP
Digital Bus Common Mode Filtering
N9030B PXA Signal Analyzer Service Guide
The signal then passes through a 30 MHz to 90 MHz tripler. A 0 to 5V, 30
MHz square wave is generated. Capacitors form a single-pole band pass
filter to select the 3rd harmonic, 90 MHz.
Various external noise sources can be connected to the rear panel of the
PXA Signal Analyzer. These noise sources require a very accurate 28 volt DC
power supply.
The 28 volt BNC output connector is used with the 346 series noise sources.
The Smart Noise Source (SNS) interface includes power switching for the
28 volt and 15 volt power supply. In addition, it has buffers to interface to
the SNS I2C bus for control and read back of ENR data automatically. The
SNS connector is used with the SNS series noise sources.
The signal from the ADC is sent to the Digital Signal Processor.
The Digital Bus is a real time digital interface. It is sometimes referred to as
Messenger or LVDS. The implementation on the Digital IF is unidirectional,
meaning it can only source data, not receive it. Common mode filtering is
required to translate the digital ground referenced signals to analog ground
at the rear panel.
239