Frequency (Hz)

-60

-40

-20

0

20

100

1k

10k

100k

1M

4

1

C

3

4

2

5

R

Gain

R

1

f

1 R R C C

2

S

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

21

OPA376-Q1, OPA2376-Q1, OPA4376-Q1

www.ti.com

SBOS549B – APRIL 2011 – REVISED JUNE 2016

Product Folder Links: OPA376-Q1 OPA2376-Q1 OPA4376-Q1

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Copyright © 2011–2016, Texas Instruments Incorporated

Typical Application (continued)

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.

(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 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 multi-stage active filter solutions within minutes.

8.2.2 Application Curve

Figure 31. Low-Pass Filter Transfer Function

9 Power Supply Recommendations

The OPAx376-Q1 family of devices is specified for operation from 2.2 V to 5.5 V (±1.1 V to ±2.75 V); many

specifications apply from –40°C to +125°C. Parameters that can exhibit significant variance with regard to

operating voltage or temperature are presented in the Typical Characteristics section.