TS616 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TS616' PDF : 36 Pages View PDF
TS616
9.1
Choosing the feedback circuit
The bias of an inverting amplifier
A resistance is necessary to achieve good input biasing, such as resistance R, shown in
Figure 66.
The magnitude of this resistance is calculated by assuming the negative and positive input
bias current. The aim is to compensate for the offset bias current, which could affect the
input offset voltage and the output DC component. Assuming Ib-, Ib+, Rin, Rfb and a zero
volt output, the resistance R is:
R = Rin // Rfb
Figure 66. Compensation of the input bias current
Rfb
Ib-
Rin
_
Vcc+
TS616
+
Ib+
Vcc-
R
Output
Load
9.2
Active filtering
Figure 67. Low-pass active filtering - Sallen-Key
C1
R1
IN
R2
+
C2
TS616
_
Rfb
RG
910Ω
OUT
25Ω
From the resistors Rfb and RG, we can directly calculate the gain of the filter in a classic non-
inverting amplification configuration:
AV
=
g
=
1 + R-----f--b-
Rg
We assume the following expression as the response of the system:
Tjω
=
V-----o----u---t--j-ω-
Vinjω
=
--------------------g--------------------
1
+
2ζ
ω-j--ω-c
+
(---j--ω---)--2-
ωc2
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