MCP606 Microchip Technology, MCP606 Datasheet - Page 15

• Manufacturer Part Number: MCP606
• Description: 2.5V to 5.5V Micropower CMOS Op Amps
• Manufacturer: Microchip Technology

3.6.3
The two op-amp instrumentation amplifier shown in
Figure 3-12 serves the function of taking the difference
of two input voltages, level shifting then and providing
a single output. This configuration is best suited for
higher gains. (gain > 3 V/V) is shown in Figure 3-12.
The key specifications that make the MCP606/607/
608/609 family appropriate for this application circuit is
low input bias current, low offset voltage and high com-
mon-mode rejection. The reference voltage of this cir-
cuit is supplied to the first op amp in the signal chain.
Typically, this voltage is half of the supply voltage in a
single supply environment.
FIGURE 3-12: Two Op-Amp Instrumentation
3.6.4
A classic, three op amp instrumentation amplifier is
illustrated in Figure 3-15. The input operational amplifi-
ers in this circuit provide signal gain. The output opera-
tional amplifier converts the signal from two inputs to a
single ended output with a difference amplifier. The
gain of this circuit is simply adjusted with one resistor,
R
this instrumentation amplifier is capable of spanning a
wide range. Most typically this node is referenced to
half of the supply voltage in a signal supply application.
V
V
G
*Bypass Capacitor, 0.1 F
REF
2000 Microchip Technology Inc.
2
. The reference voltage of the difference stage of
R
1
V
OUT
TWO OP-AMP INSTRUMENTATION
AMPLIFIER
THREE OP-AMP INSTRUMENTATION
AMPLIFIER
MCP607
=
1
/
2
V
R
V
1
Amplifier
2
DD
–
V
*
V
2
1
R
1
G
+
R
2
R
------ -
R
1
2
+
2R
----------
R
G
1
MCP607
1
+
/
2
R
V
1
REF
V
OUT
FIGURE 3-13: Three Op-Amp Instrumentation
3.6.5
In Figure 3-14, the low input offset voltage of the
MCP606 is used to implement a circuit with a high gain.
This precision measurement can easily be disrupted by
changing the output current drive of the device that is
doing the amplification work. Consequently the preci-
sion amplifier configuration is followed by a MCP601
amplifier which is capable of driving higher currents.
Since the two amplifiers are housed in separate pack-
ages, there is minimal change in offset voltage of the
MCP606 due to loading effects.
FIGURE 3-14: Precision Gain with Good Load
MCP606/607/608/609
V
*Bypass Capacitor, 1 F
V
*Bypass Capacitor, 1 F
R
V
IN
2
V
G
1
OUT
R
Precision Amplifier
1
PRECISION GAIN WITH GOOD LOAD
ISOLATION
MCP607
=
MCP607
1
/
2
V
1
/
2
1
R
V
R
S
2
2
–
V
Amplifier
Isolation
–
MCP606
+
2
*
1
R
V
+
DD
2
R
R
2R
----------
R
3
3
G
*
2
V
REF
R
------ -
R
R
4
3
4
MCP607
DS11177B-page 15
–
+
MCP601
+
R
1
/
2
V
4
V
DD
REF
Buffer
V
S
R
------ -
R
*
*
4
3
V
V
OUT
OUT