Keysight CXG, EXG, and MXG X-Series Signal Generators Service Guide 75
Self Test
Self Test Descriptions
204 Internal Oscillator Check
This test checks the proper operation of the internal 10MHz reference
oscillator. For triple-loop boards, the 10MHz reference oscillator is an OCXO.
For single-loop boards, the 10MHz reference oscillator is a TCXO. This test
adjusts the tune DAC to nudge the internal 10MHz reference. By moving this
internal 10 MHz reference frequency, the 100 MHz MUAT oscillator will also
move by a factor of 10. Thus, the MUAT tuning voltage will change to move the
oscillation frequency.
205 PLL Integrator
This test checks the 100 MHz PLL integrator and checks all the bandwidths.
For each condition, the test first rails the integrator by opening the PLL loop.
Then the test will close the loop with the appropriate gain and bandwidth
setting.
206 PLL Divider (CXG/EXG)
This test checks the 100 MHz PLL by changing the reference divider number
and keeping the 10 MHz internal reference constant. This requires that the 10
MHz reference is connected to the flexible reference phase detector. Thus, this
test can only be tested with single-loop boards.
207 PLL Unlock Detector (CXG/EXG)
This test checks the reference PLL unlock detector circuit. A window
comparator is used to detect the MUAT tune voltage. The test adjusts the
tuning voltage by adjusting the PLL divide number. Thus, the test can only be
run utilizing the flexible reference phase detector and thus can only be tested
with single-loop boards.
208 Reference Detectors
This test checks the 500 MHz and the 1 GHz signals by measuring their
respective detector voltages.
300 Synthesizer Self Tests
The Synthesizer Self Tests are designed to test the synthesizer section of the
A3 RF assembly. For triple-loop RFs, all tests are available. However, for
single-loop RFs, tests for the offset loop, FranN loops, and some of the sum
loop are not available because of the physical differences in the hardware.
301 Synthesizer Voltages
This test checks the voltages used for the synthesizer section.
302 Offset Pretune DAC (MXG)
This test checks to make sure the synthesizer offset pretune DAC circuitry is
working.
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