Teledyne LeCroy QPHY-DDR2 - Manual (Page 36)

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QPHY-DDR2-OM-E Rev A
tJIT(per), Clock Period Jitter
Applicable only to 667 and 800 MHz device only.
tJIT(per) is defined as the largest deviation of any single tCK from tCK(avg). This test compares the average clock
period (over 200 cycles) with each period inside the window. The smallest and largest values must be within
limits.
tJIT(per) = Min/max of {tCKi - tCK(avg)} where i=1 to 200
Measured on both the rising and the falling edge.
There are different limit depending on whether the DLL is already locked or not:

tJIT(per) defines the single period jitter when the DLL is already locked.

tJIT(per,lck) uses the same definition for single period jitter, during the DLL locking period only.
A configuration variable allows to define which limit to use.
tJIT(cc), Cycle to Cycle Period Jitter
Applicable only to 667 and 800 MHz device only.
tJIT(cc) is defined as the difference in clock period between two consecutive clock cycles. This test compares the
smallest and largest values of the difference between any two consecutive clock cycles inside a 200 cycles
window.
tJIT(cc) = Min/max of {tCKi+1 – tCKi} where i = 1 to 199
Measured on both the rising and the falling edge.
There are different limit depending on whether the DLL is already locked or not:

tJIT(cc) defines the cycle to cycle jitter when the DLL is already locked.

tJIT(cc,lck) uses the same definition for cycle to cycle jitter, during the DLL locking period only.
A configuration variable allows to define which limit to use.
tERR(n per), Cumulative Error
Applicable only to 667 and 800 MHz device only.
tERR is defined as the cumulative error across multiple consecutive cycles from tCK(avg). This test compares the
average clock period (over 200 cycles) with each n-bit period inside the window. The smallest and largest values
must be within limits.
There are 6 different tests:
tERR(2per), tERR (3per), tERR (4per), tERR (5per), tERR (6-10per) and tERR (11-50per)
tERR(nper) = Min/max of {SUM(tCKi) - n x tCK(avg)}
where i=1 to n and:
n = 2 for tERR(2per)
n = 3 for tERR(3per)
n = 4 for tERR(4per)
n = 5 for tERR(5per)