OPA376 Datasheet, PDF (20/42 Pages) Burr-Brown (TI) – Precision, Low Noise, Low Quiescent Current, Operational Amplifier

OPA376, OPA2376, OPA4376
SBOS406G – JUNE 2007 – REVISED DECEMBER 2015
www.ti.com
8.2 Typical Application
Low-pass filters are commonly employed in signal processing applications to reduce noise and prevent aliasing.
The OPA376 is ideally suited to construct high-speed, high-precision active filters. Figure 30 shows a second-
order, low-pass filter commonly encountered in signal processing applications.
Input
R4
2.94 k
R1
590
R3
499
C2
39 nF
C5
1 nF
±
+
OPA376
Output
Figure 30. Typical Application Schematic
8.2.1 Design Requirements
Use the following parameters for this design example:
• Gain = 5 V/V (inverting gain)
• Low-pass cutoff frequency = 25 kHz
• Second-order Chebyshev filter response with 3-dB gain peaking in the passband
8.2.1.1 Detailed Design Procedure
The infinite-gain multiple-feedback circuit for a low-pass network function is shown in Figure 30. Use Equation 1
to calculate the voltage transfer function.
Output _s
Input
s²
1 R₁R₃C₂C₅
s C₂ 1 R₁ 1 R₃ 1 R₄ 1 R₃R₄C₂C₅
(1)
This circuit produces a signal inversion. For this circuit, the gain at dc and the low-pass cutoff frequency are
calculated by Equation 2:
Gain ^R4
R₁
f_C
1
2S
1 R₃R₄C₂C₅
(2)
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
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