DRAM Detective · Case File 1.9
Level the Day and Night
A clock that samples on both edges needs its day (high) and night (low) to be equal.
A clock's day (high) and night (low) must be the same length…
day = high · night = low · dawn = rising edge · dusk = falling edge
duty cycle = high ÷ period
dawn · rising
dusk · falling
even
odd
50 / 50 — day = night, both eyes wide
dawn · rising
dusk · falling
even
odd
60 / 40 — day too long, the odd eye (night) shrinks
dawn · rising
dusk · DCA
even
odd
DCA moves dusk back → 50 / 50 again, both eyes wide
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Step 1 of 3
A clock that samples on both edges must level its day and night — shorten one half and that half's eye shrinks.