adc_clk_mmcm_integration.md was a 164-line "Step 1: modify
ad9484_interface_400m.v / Replace the BUFG instantiation with
adc_clk_mmcm" walkthrough for an integration that is already
shipped in the production RTL.
ad9484_interface_400m.v lines 68-102 already document the BUFIO/BUFG/
MMCME2 topology inline ("MMCME2 jitter-cleaning wrapper replaces the
direct BUFG. The PLL feedback loop attenuates input jitter from ~50 ps
to ~20-30 ps..."). adc_clk_mmcm.v has the wrapper itself with its own
header. constraints/adc_clk_mmcm.xdc carries the timing rationale.
A future engineer reading the integration recipe could mistake the
already-integrated feature for unfinished work and try to redo the
"Step 1: modify" edits — actively harmful.
Jason
f9e64c420b