MCP607-I/SNG Microchip, MCP607-I/SNG Datasheet - Page 19

• Manufacturer Part Number: MCP607-I/SNG
• Description: dual 25 ua, 2.5v op amp, i temp...
• Manufacturer: Microchip

4.8.4
A classic, three op amp instrumentation amplifier is
illustrated in
provide differential signal gain and a common mode
gain of +1. The output op amp is a difference amplifier,
which converts its input signal from differential to a sin-
gle ended output; it rejects common mode signals at its
input. The gain of this circuit is simply adjusted with one
resistor (R
referenced to mid-supply (V
applications.
FIGURE 4-12:
Instrumentation Amplifier.
© 2009 Microchip Technology Inc.
V
V
2
1
V OUT
G
THREE OP AMP
INSTRUMENTATION AMPLIFIER
). The reference voltage (V
R
Figure
=
G
R
R
MCP607
(
2
2
MCP607
V 1 V 2
½
–
½
4-12. The two input op amps
Three Op Amp
) 1
R
R
⎛
⎜
⎝
3
3
+
2R
---------
R G
DD
2
⎞ R
⎟
⎠
/2) in single-supply
R
R
⎛
⎜
⎝
----- -
R
MCP606
4
4
4
3
⎞
⎟
⎠
+
REF
V REF
) is typically
V
V
OUT
REF
4.8.5
In
provide a high gain to the input signal (V
MCP606’s low offset voltage makes this an accurate
circuit.
The MCP601 is configured as a unity-gain buffer. It
isolates the MCP606’s output from the load, increasing
the high-gain stage’s precision. Since the MCP601 has
a higher output current, with the two amplifiers being
housed in separate packages, there is minimal change
in the MCP606’s offset voltage due to loading effect.
FIGURE 4-13:
Load Isolation.
Figure
V
IN
4-13, the MCP606 op amps, R
PRECISION GAIN WITH GOOD
LOAD ISOLATION
R
1
V OUT
MCP606/7/8/9
R
MCP606
=
Precision Gain with Good
2
V
IN
(
1
+
R
2
⁄
R
MCP601
1
DS11177F-page 19
)
1
V
IN
OUT
and R
). The
2