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Amplifiers
A.3.6
Noninverting Op Amp with Noninverting Negative Reference
The transfer equation takes the form of Y = mX – b and is given in Equation A–6.
V OUT
V IN
R 2
R 1
R 2
R F R G
R G
V REF
R 1
R 1
R 2
R F R G
R G
A–6
The transfer function slope is positive, and the dc intercept is negative. The reference is
terminated in R 1 and R 2 . R 1 and R 2 can be selected independent of R F and R G to obtain
the desired slope and dc intercept. The price for the extra degree of freedom is two resistors.
+ 5 V
R G
R F
R 1
+V CC
_
+
V OUT
V OUT — 1 V/Div
V IN
R 2
V REF
– 5 V
– 5 V
V IN — 1 V/Div
+ 5 V
V IN = 10 Vp-p
V REF = –1 V
V CC = 5 V Op Amp = TLV247x
R 1 = R 2 = R G = R F = 10 k
Figure A–10. Noninverting Op Amp with Noninverting Negative Reference
A-10