Datasheet

TL03x, TL03xA
ENHANCED-JFET LOW-POWER LOW-OFFSET
OPERATIONAL AMPLIFIERS
SLOS180C − FEBRUARY 1997 − REVISED DECEMBER 2001
43
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
high-Q notch filter
In general, Texas Instruments enhanced-JFET operational amplifiers serve as excellent filters. The circuit in
Figure 64 provides a narrow notch at a specific frequency. Notch filters are designed to eliminate frequencies
that are interfering with the operation of an application. For this filter, the center frequency can be calculated as:
f
O
+
1
2p R1 C1
With the resistors and capacitors shown in Figure 64, the center frequency is 1 kHz. C1 = C3 = C2 + 2 and
R1 = R3 = 2 × R2. The center frequency can be modified by varying these values. When adjusting the center
frequency, ensure that the operational amplifier has sufficient gain at the frequency required.
−
+
0.2
−8
Gain − dB
f − Frequency − kHz
2
2
0.4 0.6 0.8 1 0.2 0.4 0.6 0.8
−7
−6
−5
−4
−3
−2
0
1
R1 R3
1.5 MΩ
C2
220 pF
R3 750 kΩ
C1
C3
110 pF
110 pF
1.5 MΩ
15 V
−15 V
TL03x
V
O
V
I
−1
Figure 64. High-Q Notch Filter