Check Source Assembly; Filter And Clock Distribution Board; Test Acquisition Board - Keysight 8990B Service Manual

2 Theory of Operation

Check Source Assembly

The check source assembly verifies that the wideband power sensor is operational
by outputting an RF signal.

Filter and Clock Distribution Board

The filter and clock distribution board provides a 10 MHz clock conditioning
source to sync the main board assembly with the test acquisition board. It
performs filtering function when the 8990B is used with a sensor at a low
frequency RF signal.

Test Acquisition Board

The test acquisition board contains the TUT modules, onboard ADC, clock
distribution, data management ASICs, external acquisition memory, ADC,
communication and programming FPGA, and supporting power supply circuitry.
The main function of this board is as follows.
– Provide scope measurement function
– Stable internal crystal ~1.4 ppm
– Power conditioning circuitry
– Trigger/sync to the peak power analyzer
– Control the front panel
– Integrate with the PC motherboard through PCIE
58 Keysight 8990B Service Guide