Agilent Technologies Infiniium 90000 A Service Manual page 144

Chapter 7: Theory of Operation
Block-Level Theory
Motherboard
The motherboard provides all system control and interface functions for the oscilloscope. It
contains a CPU, ROM, and RAM; keyboard and mouse interfaces, serial and parallel interfaces,
CDROM, hard disk drive interface, PCI buses, etc.
Display Board
The Display Board controls the flat-panel display monitor. It translates the video signals from
the motherboard's on-board video system to the Low Voltage Differential Signal (LVDS) signals
that drive the monitor.
On/Off Board
The On/Off board interfaces with the motherboard to provide the on-off switch function and the
backplane to provide the probe compensation output. Power indicator LEDs backlight the on-
off pushbutton and are driven by the motherboard. The probe compensation lugs connect to the
calibrator output on the backplane through an SMB connector coax cable. An ESD protection
diode sits on the On-Off board, connecting the signal and ground probe compensation lugs.
Main FPGA
The main FPGA is the only communication link from the oscilloscope hardware to the PC system.
All system controls and data must pass through the main FPGA. It contains a number of registers
that can be used to control peripherals, configure, and communicate with other FPGAs, and pass
sampled data to the PC. Figure 7-5 shows the main connections to the FPGA. In addition, the
FPGA generates PCI interrupts for special events such as front-end overload, the timer done,
and a stopped cooling fan.
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