SBOS110C May   1998  – March 2023 OPA2227 , OPA2228 , OPA227 , OPA228 , OPA4227 , OPA4228

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information: OPA227, OPA228
    5. 6.5 Thermal Information: OPA2227, OPA2228
    6. 6.6 Thermal Information: OPA4227, OPA4228
    7. 6.7 Electrical Characteristics: OPAx227 
    8. 6.8 Electrical Characteristics: OPAx228 
    9. 6.9 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Offset Voltage and Drift
      2. 7.3.2 Operating Voltage
      3. 7.3.3 Offset Voltage Adjustment
      4. 7.3.4 Input Protection
      5. 7.3.5 Input Bias Current Cancellation
      6. 7.3.6 Noise Performance
      7. 7.3.7 Basic Noise Calculations
      8. 7.3.8 EMI Rejection Ratio (EMIRR)
        1. 7.3.8.1 EMIRR IN+ Test Configuration
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Using the OPAx228 in Low Gains
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Three-Pole, 20 kHz Low Pass, 0.5-dB Chebyshev Filter
      3. 8.2.3 Long-Wavelength Infrared Detector Amplifier
      4. 8.2.4 High Performance Synchronous Demodulator
      5. 8.2.5 Headphone Amplifier
      6. 8.2.6 Three-Band Active Tone Control (Bass, Midrange, and Treble)
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 TINA-TI™ Simulation Software (Free Download)
        2. 9.1.1.2 TI Reference Designs
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.8 EMI Rejection Ratio (EMIRR)

The electromagnetic interference (EMI) rejection ratio, or EMIRR, describes the EMI immunity of operational amplifiers. An adverse effect that is common to many operational amplifiers is a change in the offset voltage as a result of RF signal rectification. An operational amplifier that is more efficient at rejecting this change in offset as a result of EMI has a higher EMIRR and is quantified by a decibel value. Measuring EMIRR can be performed in many ways, but this section provides the EMIRR IN+, which specifically describes the EMIRR performance when the RF signal is applied to the noninverting input pin of the operational amplifier. In general, only the noninverting input is tested for EMIRR for the following three reasons:

  1. Operational amplifier input pins are known to be the most sensitive to EMI, and typically rectify RF signals better than the supply or output pins.
  2. The noninverting and inverting operational amplifier inputs have symmetrical physical layouts and exhibit nearly matching EMIRR performance.
  3. EMIRR is easier to measure on noninverting pins than on other pins because the noninverting input terminal can be isolated on a printed-circuit-board (PCB). This isolation allows the RF signal to be applied directly to the noninverting input terminal with no complex interactions from other components or connecting PCB traces.

A more formal discussion of the EMIRR IN+ definition and test method is provided in application report SBOA128, EMI Rejection Ratio of Operational Amplifiers, available for download at www.ti.com. The EMIRR IN+ of the OPA227 is plotted versus frequency as shown in Figure 7-8.

GUID-0CA1FBB1-541B-4EBF-9D06-88275CAA3448-low.gifFigure 7-8 OPA227 EMIRR IN+ vs Frequency

If available, any dual and quad operational amplifier device versions have nearly similar EMIRR IN+ performance. The OPAx227 unity-gain bandwidth is 8 MHz. EMIRR performance below this frequency denotes interfering signals that fall within the operational amplifier bandwidth.

Table 7-1 shows the EMIRR IN+ values for the OPA227 at particular frequencies commonly encountered in real-world applications. Applications listed in Table 7-1 can be centered on or operated near the particular frequency shown. This information can be of special interest to designers working with these types of applications, or working in other fields likely to encounter RF interference from broad sources, such as the industrial, scientific, and medical (ISM) radio band.

Table 7-1 OPAx227 EMIRR IN+ for Frequencies of Interest
FREQUENCYAPPLICATION/ALLOCATIONEMIRR IN+
400 MHzMobile radio, mobile satellite and space operation, weather, radar, UHF35.7 dB
900 MHzGSM, radio communication and navigation, GPS (to 1.6 GHz), ISM, aeronautical mobile, UHF47.8 dB
1.8 GHzGSM, mobile personal comm. broadband, satellite, L-band68.8 dB
2.4 GHz802.11b/g/n, Bluetooth® mobile personal communication, ISM, amateur radio and satellite, S-band69.8 dB
3.6 GHzRadiolocation, aero communication and navigation, satellite, mobile, S-band78 dB
5 GHz802.11a/n, aero communication and navigation, mobile communication, space and satellite operation, C-band88.4 dB