SBOS492G June   2009  – August 2026 OPA2354A-Q1 , OPA354A-Q1 , OPA4354-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Operating Voltage
      2. 6.3.2 Rail-to-Rail Input
      3. 6.3.3 Rail-to-Rail Output
      4. 6.3.4 Output Drive
      5. 6.3.5 Video
      6. 6.3.6 Driving Analog-to-Digital Converters
      7. 6.3.7 Capacitive Load and Stability
      8. 6.3.8 Wideband Transimpedance Amplifier
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Transimpedance Amplifier
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Optimizing The Transimpedance Circuit
        3. 7.2.1.3 Application Curve
      2. 7.2.2 High-Impedance Sensor Interface
      3. 7.2.3 Driving ADCs
      4. 7.2.4 Active Filter
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Power Dissipation
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.2.4 Active Filter

The OPAx354-Q1 family of devices is designed for active filter applications that require a wide bandwidth, fast slew rate, low-noise, single-supply operational amplifier. Figure 7-6 shows a 500kHz, second-order, low-pass filter using the multiple-feedback (MFB) topology. The components are selected to provide a maximally-flat Butterworth response. Beyond the cutoff frequency, roll-off is
–40dB/dec. The Butterworth response is designed for applications requiring predictable gain characteristics, such as the anti-aliasing filter used in front of an ADC.

One point to observe when considering the MFB filter is that the output is inverted relative to the input. If this inversion is not required, or not desired, a noninverting output can be achieved through one of the following options:

  1. Adding an inverting amplifier
  2. Adding an additional second-order MFB stage
  3. Using a noninverting filter topology, such as the Sallen-Key (see Figure 7-7).

MFB and Sallen-Key, low-pass and high-pass filter synthesis is accomplished using TI’s FilterPro™ program. This software is available as a free download on www.ti.com.

OPA354A-Q1 OPA2354A-Q1 OPA4354-Q1 Second-Order Butterworth 500kHz Low-Pass FilterFigure 7-6 Second-Order Butterworth 500kHz Low-Pass Filter
OPA354A-Q1 OPA2354A-Q1 OPA4354-Q1 OPAx354-Q1 Configured as a Three-Pole, 20kHz, Sallen-Key FilterFigure 7-7 OPAx354-Q1 Configured as a Three-Pole, 20kHz, Sallen-Key Filter