+
±
C1
Z1/6
Z4/9
Z5/10
Z3/8
Z2/7
VOUT
V+
INA/B
C3
V-
R1/3
R2/4
C2/4
REFA/B
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Schematic and PCB Layout
11
SBOU193 – July 2017
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Copyright © 2017, Texas Instruments Incorporated
DUAL-DIYAMP-EVM
Figure 14
displays the PCB layout of the top layer of the difference amplifier with reference buffer circuit
configuration.
Figure 14. Difference Amplifier with Reference Buffer Top Layer PCB Layout
3.5
Multiple Feedback Active Filter
Figure 15
shows the schematic for the multiple feedback (MFB) active filter circuit configuration.
Figure 15. Multiple Feedback Active Filter Schematic
The MFB topology (sometimes called infinite gain or Rauch) is often preferred due to low sensitivity to
component variation. The MFB topology creates an inverting second-order stage.
The MFB filter circuit can be configured as a low-pass filter, high-pass filter, or band-pass filter based on
the component selection of Z1/6 through Z5/10.
Table 3
displays the type of passive component that
should be chosen for Z1/6 through Z5/10 for each filter configuration.
Table 3. MFB Filter Type Component Selection
Pass-Band Filter
Type
Type of
Component (Z1/6)
Type of
Component (Z2/7)
Type of
Component (Z3/8)
Type of
Component (Z4/9)
Type of
Component (Z5/10)
Low Pass
R1/6
C2/7
R3/8
R4/9
C5/10
High Pass
C1/6
R2/7
C3/8
C4/9
R5/10
Band Pass
R1/6
R2/7
C3/8
C4/9
R5/10
