SLVU006A Datasheet, PDF (21/28 Pages) Texas Instruments – UNIVERSAL OPERATIONAL AMPLIFIER EVALUATION MODULE

Sallen-Key High-Pass Filter
3.3 Sallen-Key High-Pass Filter
Figure 3–2 shows area 200 equipped with a dual operational amplifier
configured as a second-order Sallen-Key high-pass filter using single-supply
power input.
Basic setup is done by proper choice of resistors R and mR, and capacitors
C and nC. Note that capacitors should be used for components R210 and
R211, and a resistor for C201. The transfer function for the circuit as shown
is:
ȧȡȢ ȧȣȤ ^{+ V}_OUT ^V_IN
2
ǒ Ǔ_{ń ) – f fo}
2 ^VREF2
ǒ Ǔ ǒ Ǔ ₎ ǒ _ń Ǔ _{ń ń 1 j Q f fo – f fo}
Where:
+ _Ǹ f_o
1
2p m n RC
And
Q
+
n^Ǹm)
n
1
The TL431 adjustable precision shunt regulator, configured as shown,
provides a low impedance reference for the circuit at about 1/2 V2+ in a 5 V
system. Another option is to adjust resistors R215 and R216 for the desired
+ ǒ ⁾ Ǔ ^{VREF2 voltage. The formula for calculating VREF2 is:}
VREF2
2.50
V
R215 R216
R216
Example Circuits
3-3