User guide

Table 29
Parameter Name Pass/Fail
Q High Level Nr. Points
Q High Level R^2
Q Low Level
Q Low Level Std.Dev
Q Low Level Nr. Points
Q Low Level R^2
For some of these parameters, pass/fail limits can be set, as indicated in the table.
The numerical Q-factor parameters are defined as follows:
• Q Factor
The Q-factor is calculated as:
where μ
1,0
is the mean level of the 1 and 0 rails, respectively, and σ
1,0
is the
standard deviation of the noise distribution on the 1 and 0 rails.
• Q Optimum Threshold
The Q Optimum Decision Threshold is calculated as:
Optimum Decision Threshold =
s
0
m
1
+ s
1
m
0
s
1
+ s
0
• Q Residual BER
The Q Residual BER is the expected BER at the Optimum Decision Threshold.
It is calculated as:
e
Q
opt
2p
- ( Q
2
/2)
BER =
Numbers below 1e-255 are expressed as zero.
• Q High Level
6 Advanced Analysis
280 Agilent J-BERT N4903B High-Performance Serial BERT