Chapter 11 535
Synthesizer Section
General PLL Troubleshooting
Figure 11-5 PLL Locked at Wrong Frequency
Unlocked PLL
An unlocked PLL can be caused by problems inside or outside the PLL.
Troubleshoot this problem by working backward from the oscillator as
described in the steps below. Numbers in the following text identify
items in Figure 11-6 on page 536.
1. The loop integrator output voltage (1) should be attempting to tune
the oscillator to the correct frequency:
The voltage at (1) should increase as the frequency increases on
all of the PLLs:
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