c
6
5
1
2
R
C
=
´ p ´
´
f
c
2
2
1
2
R
C
=
´ p ´
´
f
2
1
R
VOUT
1
VIN
R
æ
ö
=
+
ç
÷
è
ø
+
±
V-
V+
C3
+
±
VIN
VOUT
C5
R6
R1
R2
VREF
C1
C2
R3
C4
R5
R4
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Schematic and PCB Layout
17
SBOU193 – July 2017
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DUAL-DIYAMP-EVM
3.10 Parallel Op Amps
Figure 25
displays the schematic of the parallel op-amp circuit configuration.
Figure 25. Parallel Op Amp Schematic
Parallel op amps are used to increase the maximum current supplied to a load. Placing two op amps in
parallel doubles the maximum current into the load compared to using a single amplifier. This circuit is
useful for applications that require driving low impedance loads or applications that require more current
supplied into a load than a single op amp can typically supply.
There are multiple ways to configure the non-inverting amplifier circuit configuration. The following cases
show the two primary use-case configurations for this circuit.
Case 1: Standard non-inverting configuration
This circuit can be configured into a standard non-inverting circuit by shorting C1 and C5 with a 0-
Ω
resistor and leaving R6 unpopulated.
Equation 19
displays the transfer function of the non-inverting amplifier circuit configuration shown in
Figure 25
.
where
•
C
1
is shorted with a 0-
Ω
resistor
•
C
5
is shorted with a 0-
Ω
resistor
•
R
6
is unpopulated
(19)
Capacitor C2 provides the option to filter the output.
Equation 20
calculates the cut-off frequency of the
filter.
(20)
Case 2: AC-coupled non-inverting amplifier configuration
This circuit can be configured into an ac-coupled, non-inverting circuit by populating C1 and C5 with
capacitors and R6 with a resistor. Test point VREF is used to set the dc biasing of the circuit. The dc
biasing is typically set to one half of the supply voltage of the amplifier.
Populating C5 ac couples the input of the circuit.
Equation 21
calculates the corner frequency of the high-
pass filter created by C5 and R6.
(21)
