MC3301, LM2900, LM3900
Figure 12. Inverting Amplifier
Figure 13. Noninverting Amplifier
R
f
R
i
R
f
R
510 k
(R )(A )
f j
f
A = –
V
510 k
A =
1
V
26
+(mA)
R +
i
1
l
in
for
R
i
ωC
+15 V
V
CC
+15 V
0.1 µF
V
CC
–
BW = 250 kHz
V
1.0 µF
V
in
–
+
0.1 µF
R
V
O
l +
in
i
O
+
C
51 k
+
+
V
in
+5.0 µF
R
i
10 k
R
10 k
R
r
510 k
r
1.0 M
1.0 M
+15 V
A = 10 BW = 150 kHz
V
+15 V
2. Gain Determination
A. Inverting Amplifier
The lower corner frequency is determined by the
coupling capacitors to the input and load resistors.
The upper corner frequency will usually be
determined by the amplifier internal compensation.
The amplifier unity gain bandwidth is typically
400 kHz with 20 dB of closed loop gain or 40 kHz
with 40 dB of closed loop gain. The exception to this
occurs at low gains where the input resistor
selected is large. The pole formed by the amplifier
input capacitance, stray capacitance and the input
resistor may occur before the closed loop gain
intercepts the open loop response curve. The
inverting input capacity is typically 3.0 pF.
The amplifier is normally used in the inverting mode.
The input may be capacitively coupled to avoid
upsetting the DC bias and the output is normally
capacitively coupled to eliminate the DC voltage
across the load. Note that when the output is
capacitively coupled to the load, the value of I
sink
becomes a limitation with respect to the load driving
capabilities of the device if it is direct coupled. In this
configuration, the AC gain is determined by the ratio
of R to R , in the same manner as for a conventional
f
i
operational amplifier:
R
R
f
i
A
V
=
Figure 14. Inverting Amplifier with
Arbitrary Reference
Figure 15. Inverting Amplifier with
A = 100 and V = V
V
r
CC
510 k
R
f
V
CC
+15 V
0.1 µF
C*
R
i
–
0.1 µF
V
in
–
V
in
5.1 k
V
O
V
O
+
+
10 k
1.0 M
R
r
l
in
+
V
+15 V
r
f = 300 Hz, f = 50 kHz
L
V
H
V
r
A = 100
*Select for low frequency response.
2–118
MOTOROLA ANALOG IC DEVICE DATA
ONSEMI [ ONSEMI ]
