August
2004, Issue 169
Test Your
EQ:
|
Answer
5—The
CMRR of the circuit is extremely sensitive to how well
the resistors are matched; specifically, the RY/RX
ratio of the upper half must match RY/RX
of the lower half. For example, resistors with 1% tolerance
must be used in order to guarantee a CMRR of just 40 dB,
and 0.01% resistors are needed to get to 80 dB.
Contributor:
David Tweed
