Applications
Common-Mode Rejection
The following procedure shows how to eliminate unwanted ac
input-power frequency components. Similar methods could be
used to eliminate other unwanted frequency components or to
provide a dc offset.
1. Apply the signal containing the unwanted line-frequency com
ponents to the C H 1 input connector.
2. Apply a line-frequency signal to the CH 2 input connector. To
maximize cancellation, the signal applied to Channel 2 must
be in phase with the unwanted line frequency component of
the Channel 1 input.
CH 1— SIGNAL
WITH UNWANTED
0 "!::
—
.T S
N
LINE FREQUENCY T : U
*
\
COMPONENT j
CH 2— SIGNAL
FROM LINE ’5
FREQUENCY
SOURCE
INVERTED
Nf
N
NJ
'iTrr
© ft
SrJT
X
§ § '
C H I AND CH 2 SIGNALS
10
SIGNAL WITH
LINE FREQUENCY
COMPONENT
CANCELED OUT
ii
' l l
iZ
lI
.1
r
RESULTANTSIGNAL
4 2 0 7 -1 5
Figure 3-3.Common-mode rejection.
2225 Operators
3-5
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