ZHCSGC1F June   2017  – March 2021 OPA145 , OPA2145

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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: OPA145
    5. 6.5 Thermal Information: OPA2145
    6. 6.6 Electrical Characteristics: VS = 4.5 V to 36 V; ±2.25 V to ±18 V
    7. 6.7 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 Capacitive Load and Stability
      2. 7.3.2 Output Current Limit
      3. 7.3.3 Noise Performance
      4. 7.3.4 Basic Noise Calculations
      5. 7.3.5 Phase-Reversal Protection
      6. 7.3.6 Electrical Overstress
      7. 7.3.7 EMI Rejection
      8. 7.3.8 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 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
    3. 8.3 System Examples
      1. 8.3.1 16-Bit, 100-kSPS, Fully Differential Transimpedance Imaging and Measurement
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 TINA-TI™ SImulation Software (Free Download)
        2. 11.1.1.2 WEBENCH Filter Designer Tool
        3. 11.1.1.3 TI Precision Designs
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 支持资源
    5. 11.5 Trademarks
    6. 11.6 静电放电警告
    7. 11.7 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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7.3.7 EMI Rejection

The electromagnetic interference (EMI) rejection ratio, or EMIRR, describes the EMI immunity of operational amplifiers. An adverse effect that is common to many op amps is a change in the offset voltage as a result of RF signal rectification. An op amp 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 op amp. In general, only the noninverting input is tested for EMIRR for the following three reasons:

  • Op amp input pins are known to be the most sensitive to EMI, and typically rectify RF signals better than the supply or output pins.
  • The noninverting and inverting op amp inputs have symmetrical physical layouts and exhibit nearly matching EMIRR performance.
  • EMIRR is easier to measure on noninverting pins than on other pins because the noninverting input terminal can be isolated on a 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.
High-frequency signals conducted or radiated to any pin of the operational amplifier result in adverse effects, as the amplifier would not have sufficient loop gain to correct for signals with spectral content outside the amplifier bandwidth. Conducted or radiated EMI on inputs, power supply, or output may result in unexpected dc offsets, transient voltages, or other unknown behavior. Be sure to properly shield and isolate sensitive analog nodes from noisy radio signals and digital clocks and interfaces. Figure 7-5 shows the effect of conducted EMI to the power supplies on the input offset voltage of OPAx145.

The EMIRR IN+ of the OPAx145 is plotted versus frequency as shown in Figure 7-4. The OPAx145 unity-gain bandwidth is 5.5 MHz. EMIRR performance below this frequency denotes interfering signals that fall within the op amp bandwidth.See EMI Rejection Ratio of Operational Amplifiers, available for download from www.ti.com.

GUID-57B2FA91-16A0-46FC-BC5D-9323ED9CC481-low.pngFigure 7-4 OPAx145 EMIRR IN+
GUID-F086096D-858D-4EA1-AC1C-4BFA22EDD523-low.pngFigure 7-5 OPAx145 EMI-Induced Input Offset Voltage (Power Supplies)

Table 7-1 lists the EMIRR IN+ values for the OPAx145 at particular frequencies commonly encountered in real-world applications. Applications listed in Table 7-1 may be centered on or operated near the particular frequency shown. This information may 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 OPAx145 EMIRR IN+ for Frequencies of Interest
FREQUENCYAPPLICATION OR ALLOCATIONEMIRR IN+
400 MHzMobile radio, mobile satellite, space operation, weather, radar, ultra-high frequency (UHF) applications54 dB
900 MHzGlobal system for mobile communications (GSM) applications, radio communication, navigation, GPS (to 1.6 GHz), GSM, aeronautical mobile, UHF applications68 dB
1.8 GHzGSM applications, mobile personal communications, broadband, satellite, L-band (1 GHz to 2 GHz)86 dB
2.4 GHz802.11b, 802.11g, 802.11n, Bluetooth®, mobile personal communications, industrial, scientific and medical (ISM) radio band, amateur radio and satellite, S-band (2 GHz to 4 GHz)107 dB
3.6 GHzRadiolocation, aero communication and navigation, satellite, mobile, S-band100 dB
5 GHz802.11a, 802.11n, aero communication and navigation, mobile communication, space and satellite operation, C-band (4 GHz to 8 GHz)105 dB