OPA830 datasheet(40/66 Pages) TI2

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9.2.2 Active Filters

The OPA836 and OPA2836 devices are good choices for active filters. Figure 9-15 and Figure 9-16 show MFB

and Sallen-Key circuits designed using the WEBENCH® Filter Designer to implement second-order low-pass

Butterworth filter circuits. Figure 9-17 shows the frequency response.

Other MFB and Sallen-Key filter circuits offer similar performance. The main difference is the MFB is an inverting

amplifier in the pass-band and the Sallen-Key is noninverting. The primary advantage for each is the Sallen-Key

in unity gain has no resistor gain-error term, and thus no sensitivity to gain error, while the MFB has better

attenuation properties beyond the bandwidth of the operational amplifier.

OPA 836

330 pF

1.24 kW

2.80 kW

2.2 nF

Figure 9-15. MFB 100-kHz Second-Order Low-Pass Butterworth Filter Circuit

OPA836

330 pF

562 W

6.19 kW

2.2 nF

Figure 9-16. Sallen-Key 100-kHz Second-Order Low-Pass Butterworth Filter Circuit

9.2.2.1 Application Curve

-40

-30

-20

-10

10k

100k

f - Frequency - Hz

Sallen-Key

MFB

V = 5 V,

= 100 mV

OUT

Figure 9-17. MFB and Sallen-Key Second Order Low-Pass Butterworth Filter Response

OPA836, OPA2836

SLOS712J – JANUARY 2011 – REVISED MARCH 2021

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OPA830 Datasheet(PDF) 40 Page - Texas Instruments