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Butterworth Filter
2-6
Using the THS4130 EVM
Note:
Transformers are used to change the single ended signals to differential
signal or vice versa. On this EVM, they can be populated according to the
application or the experiment. The V
OCM
pin of the device may be connected
to the center-tap of the transformer, or maybe set via an external source such
as V
ref
of a data converter. If the V
OCM
pin is not connected to an external
source, it will be set at the center point of the power supply. For example, if
±5 sources are used, the V
OCM
level will be set to zero.
2.7 Butterworth Filter
An example of a Butterworth filter implemented with multiple feedback archi-
tecture is provided. The following circuit is implemented on the EVM board.
The following figures represent the circuit configuration and the component
values. The corner frequency of the filter (–3dB) is set at 1 MHz.
For verification of jumper locations and other bypass components, see the
complete EVM schematic in Figure 1–2.
Figure 2–4. Multiple Feedback Filter Circuit
+
–
THS4130
–
+
V
CC
V
EE
5 V
–5 V
100 pF
787 Ω
732 Ω
732 Ω
100 pF
787 Ω
220 pF
787 Ω
787 Ω
–1 dBm
AC
100 Ω
100 Ω