Datasheet

V
−
Single Transistor
V+
V
I
V
O
(a) Common Collector Amplifier
(Emitter Follower)
V
O
100
Ω
OTAV
I
(b) Common−C Amplifier for OTA
(Buffer)
≈
OS
G 1
V 0.7V≈
≈
OS
G 1
V 0≈
B3
C
12
R
E
R
E
R
O
=
1
g
m
G =
≈
1
1 +
1
g
m
x R
E
1
E
2
Inverting Gain
V
I
V
O
Single Transistor
(a) Common−Base
Amplifier
OTA
V
I
(b) Common−B Amplifier for OTA
OS
R
L
Noninverting Gain
V several volts
R
E
V
O
R
L
R
E
≈
B
E
3
2
C
12
G =
− ≈ −
R
L
R
E
+
g
m
1
R
L
R
E
V
OS
≈
0
V+
100
Ω
OPA615
SBOS299E –FEBRUARY 2004–REVISED SEPTEMBER 2009...................................................................................................................................... www.ti.com
Figure 37 shows the Common-C amplifier. It Figure 38 shows the Common-B amplifier. This
constitutes an open-loop buffer with low offset configuration produces an inverting gain, and the
voltage. Its gain is approximately 1 and will vary with input is low-impedance. When a high impedance
the load. input is needed, it can be created by inserting a
buffer amplifier (such as the BUF602) in series.
Figure 37. a) Common Collector Amplifier Using
a Discrete Transistor; b) Common-C Amplifier
Using the OTA Portion of the OPA615
Figure 38. a) Common Base Amplifier Using a
Discrete Transistor; b) Common-B Amplifier
Using the OTA Portion of the OPA615
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