Modifications; Gain; Opa1622Evm Schematic - Texas Instruments SoundPlus OPA1622EVM User Manual

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3

Modifications

This EVM is designed to provide access to the features of and measure the performance of the OPA1622.
Modifications of the OPA1622EVM can be made and include; adjusting the gain, phase shift, and cut-off
frequency. The schematic of the OPA1622EVM is displayed in
OPA1622EVM, see
Left Channel Input
(Right Channel Input)
3.1

Gain

Equation 1 and Equation 2
V
Left ChannelOutput
V
Right ChannelOutput
Most applications require the left and right channel to be balanced. Balancing the outputs is accomplished
by setting R2 = R4 = R6 = R8 and R1 = R3 = R5 = R7. This simplifies
Equation 3.
V
Left ChannelOutput
If the channels require unbalanced gain, the gain of each channel can be calculated using
Equation 5.
Gain
Left Channel
given
• R = R
2
Gain
Right Channel
given
• R = R
6
SBOU172 – September 2016
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Figure 13.
R1 (R5)
IN>
R3 (R7)
IN+
R4
(R8)
Figure 1. OPA1622EVM Schematic
display the transfer function of the circuit shown in
æ ö
R R
4 2
= ´ +
ç ÷
1
+
R R R
è ø
3 4 1
æ
R R
= 8 ´ + 6
ç 1
+
R R R
è
7 8 5
V
= =
Right ChannelOutput
R
2
=
R
1
and R = R
4 1 3
R
6
=
R
5
and R = R
8 5 7
OPA1622EVM SoundPlus™ Audio Operational Amplifier Evaluation Module
Copyright © 2016, Texas Instruments Incorporated
Figure
C1 (C3)
R2 (R6)
OPA1622
C2
(C4)
Copyright © 2016, Texas Instruments Incorporated
æ ö
R
2
´ + - ´ -
ç ÷
(IN ) (IN )
R
è ø
1
ö
æ ö
R
´ + - 6 ´ -
÷ (IN ) (IN )
ç ÷
è R5 ø
ø
R
2
( )
(IN ) (IN )
´ + - -
R
1
Modifications
1. For a full schematic of the
Left Channel Output
(Right Channel Output)
Figure 1.
Equation 1 and Equation 2
Equation 4
(1)
(2)
into
(3)
and
(4)
(5)
3