=

=

p

4

1

c

3

4

2

5

R

Gain

R

1

f

(1/ R R C C )

2

-

=

+

+

+

+

1 3

2

5

2

2

1

3

4

3

4

2

5

1/ R R C C

Output

(s)

Input

s

(s / C )(1/ R

1/ R

1/ R ) 1/ R R C C

Copyright © 2016, Texas Instruments Incorporated

+

±

Output

Input

R1

590

R4

2.94 k

R3

499

C2

39 nF

C5

1 nF

20

OPA207

SBOS826D – DECEMBER 2017 – REVISED OCTOBER 2019

www.ti.com

Product Folder Links: OPA207

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Copyright © 2017–2019, Texas Instruments Incorporated

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

Low-pass filters are commonly employed in signal processing applications to reduce noise and prevent aliasing.

The OPA207 is designed to construct high-precision active filters. Figure 47 shows a second-order, low-pass

filter commonly encountered in signal processing applications.

8.2 Typical Applications

8.2.1 Typical OPA207 Application

Figure 47. Typical OPA207 Application Schematic

8.2.1.1 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

8.2.1.2 Detailed Design Procedure

The infinite-gain multiple-feedback circuit for a low-pass network function is shown in Figure 47. Use Equation 1

to calculate the voltage transfer function.

(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:

(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 designers 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 to

design, optimize, and simulate complete multi-stage active filter solutions within minutes.