OPAX189 datasheet(28/58 Pages) TI2

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9 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, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The OPAx189 operational amplifier combines precision offset and drift with excellent overall performance,

making the series an excellent for many precision applications. The precision offset drift of only 0.005 µV/°C

provides stability over the entire temperature range. In addition, the device pairs excellent CMRR, PSRR, and

AOL dc performance with outstanding low-noise operation. As with all amplifiers, applications with noisy or

high-impedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1-µF

capacitors are adequate.

The following application examples highlight only a few of the circuits where the OPAx189 can be used.

9.2 Typical Applications

9.2.1 25-kHz Low-Pass Filter

OPAx189

Output

Input

590

2.94 k

499

39 nF

1 nF

Figure 9-1. 25-kHz Low-Pass Filter

9.2.1.1 Design Requirements

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

The OPAx189 devices are designed to construct high-speed, high-precision active filters. Figure 9-1 shows a

second-order, low-pass filter commonly encountered in signal processing applications.

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

OPA189, OPA2189, OPA4189

SBOS830I – SEPTEMBER 2017 – REVISED OCTOBER 2021

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OPAX189 Datasheet(PDF) 28 Page - Texas Instruments