At first glance, the circuit in the
diagram does not look out of the
ordinary, and yet, it is. This is
because it combines two characteristics
that are usually
assumed to be incompatible:
hysteresis and a high input
impedance. In a standard
op amp circuit, this is, indeed,
true, because the creation of
hysteresis is normally achieved
by positive feedback to the +ve
input of the op amp. Unfortunately,
the requisite resistance
network causes a drastic deterioration
of the original high input
impedance of the op amp.
Downloading of this magazine article is reserved for registered users only.
Discussion (0 comments)