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Other Mathenatical
Operations
As pr:eviously
indicated
the
operational
amplifier
has uses other than those jadicated
in zub-
paragraph (t) tfrrough (2).
Conplicated
transfer
firnctions
can be
simulated by using series and parallel
RC networks for the feed-
back and input
impedances.
The ci-rcuit
performance is sti1l
governed, by the basic relationship
of Equation 2.5-3.
For the
general case where three charurel networks are used, .the,Shorb
circuit
transfer
impedance of Zy and 21, must be used.
(fne short
circuit
transfer
irnpedance of a network is the ratj-o of input volt-
age to short-circuit
output current.)
The input
and feedback elements need not be linear;
therefore,
almost any non-linear
characteristic
can be approximated.
The
arnplifi-er
can also be used in conjr:-nction with diodes and z'esis-
tors
to sjmulate the non-linear
operations
of ljmiting,
dead-zone
'
generation, X2, Logf,, etc.
b.
505 Operati-onal Anplifier
DA-151
Figure 2.5-2 shows the operational
annplifier
patching terminations
and a simplified
schenatic
of high gain d-c amplifier
and summjng re-
si-stor network.
By placing
a six connector bottle
plug in the patch-
ing block as shown in Figure 2.5-3(a),
the high-gain
arnpl-ifier
is
eorurected to the sr:runi-ng resistor
network as shor^rn in Figure 2.5'3(b).
The resultant
operational
amplifier
can be used for
irrVersion,
multi-
plication
by a constant,
arrd surnmation.
The cwrputer diagran
symbol
is shomr in Figure 2.5-3G).
0n the computer diagram it
is customary
to shor.zt only those inputs
that
are used; the arnplifier
nurober is
written
inside
the tri-angular
synbol.
_ / i 7 _
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