Most of the new, fast current-feedback
op amps
have an enable input via which
it is possible to switch the device
on and off. Because of
this, the output 'floats', so that
it is permissible to couple several
outputs, provided that
only one op amp is active at
any one time. This is a property
that makes it possible to
construct a multiplexer from a
number of such op amps
which, because of the speed of
-the devices, can switch signals
up to 20~30 MHz. This is ideal
for video applications or, as in
the present design, to multiply
the number of oscilloscope inputs,
for instance, to make a
two-channel scope from a
single-channel model.
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