Chapter 11 11-9
Error Terms
Error Correction
Isolation (Crosstalk, E
XF
and E
XR
)
Description Isolation is a measure of the leakage between the test ports and the signal
paths. The isolation error terms are characterized by measuring transmission (S21, S12)
with loads attached to both ports during the error-correction procedure. Since these terms
are low in magnitude, they are usually noisy (not very repeatable). The error term
magnitude changes dramatically with IF bandwidth: a 10 Hz IF bandwidth must be used
in order to lower the noise floor beyond the crosstalk specification. Using averaging will
also reduce the peak-to-peak noise in this error term.
Significant System Components
• sampler crosstalk
Affected Measurements Transmission measurements, (primarily where the measured
signal level is very low), are affected by isolation errors. For example, transmission
measurements where the insertion loss of the device under test is large.
Figure 11-4 Typical E
XF
/E
XR
with 10 Hz Bandwidth and with 3 kHz Bandwidth
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