OPA134 Datasheet, PDF (16/22 Pages) Burr-Brown (TI) – High Performance AUDIO OPERATIONAL AMPLIFIERS TM

OPA134, OPA2134, OPA4134
SBOS058A – DECEMBER 1997 – REVISED OCTOBER 2015
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8.2 Typical Application
The OPAx134 family offers outstanding dc precision and AC performance. These devices operate up to 36-V
supply rails and offer ultralow distortion and noise, as well as 8-MHz bandwidth and high capacitive load drive.
These features make the OPAx134 a robust, high-performance operational amplifier for high-voltage professional
audio applications.
2.94 k
Input
590
499
39 nF
1 nF
±
+
Output
Figure 30. OPA134 2nd Order 30-kHz, Low Pass Filter Schematic
8.2.1 Design Requirements
• Gain = 5 V/V (inverting)
• Low pass cutoff frequency = 30 kHz
• –40 db/dec filter response
• Maintain less than 3-dB gain peaking in the gain versus frequency response
8.2.2 Detailed Design Procedure
The infinite-gain multiple-feedback circuit for a low-pass network function is shown in Figure 30. The voltage
transfer function is:
Output _s
Input
s²
1 R₁R₃C₂C₅
s C₂ 1 R₁ 1 R₃ 1 R₄ 1 R₃R₄C₂C₅
(2)
This circuit produces a signal inversion. For this circuit the gain at DC and the low pass cutoff frequency are
calculated using Equation 3.
Gain ^R4
R₁
f_C
1
2S
1 R₃R₄C₂C₅
(3)
Software tools are readily available to simplify filter design. WEBENCH® Filter Designer is a simple, powerful,
and easy-to-use active filter design program. The WEBENCH Filter Designer lets you create optimized filter
designs using a selection of TI operational amplifiers and passive components from TI's vendor partners.
Available as a web based tool from the WEBENCH® Design Center, WEBENCH® Filter Designer allows you to
design, optimize, and simulate complete multistage active filter solutions within minutes.
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