SNOSB30Q October   2008  – March 2026 LMH6554

PRODUCTION DATA  

  1.   1
  2. 1Features
  3. 2Applications
  4. 3Description
  5. 4Pin Configuration and Functions
    1.     Pin Functions
  6. 5Specifications
    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: +5 V
    6. 5.6 Typical Performance Characteristics VS = ±2.5 V
  7. 6Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
    4. 6.4 Device Functional Modes
  8. 7Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Single-Ended Input to Differential Output Operation
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Enable / Disable Operation
          2. 7.2.1.2.2 Single-Ended Input to Differential Output Operation
          3. 7.2.1.2.3 Driving Capacitive Loads
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Fully Differential Operation
      3. 7.2.3 Single Supply Operation
      4. 7.2.4 Driving Analog-to-Digital Converters
      5. 7.2.5 Output Noise Performance and Measurement
      6. 7.2.6 Balanced Cable Driver
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Power Supply Bypassing
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
      3. 7.4.3 Power Dissipation
      4. 7.4.4 ESD Protection
  9. 8Device and Documentation Support
    1. 8.1 Device Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Trademarks
  10. 9Revision History
  11.   Mechanical, Packaging, and Orderable Information

7.1 Application Information

The LMH6554 is a fully differential, current feedback amplifier with integrated output common mode control, designed to provide low distortion amplification to wide bandwidth differential signals. The common mode feedback circuit sets the output common mode voltage independent of the input common mode, as well as forcing the V+ and V− outputs to be equal in magnitude and opposite in phase, even when only one of the inputs is driven as in single to differential conversion.

The proprietary current feedback architecture of the LMH6554 offers gain and bandwidth independence with exceptional gain flatness and noise performance, even at high values of gain, simply with the appropriate choice of RF1 and RF2. Generally RF1 is set equal to RF2, and RG1 equal to RG2, so that the gain is set by the ratio RF/RG. Matching of these resistors greatly affects CMRR, DC offset error, and output balance. A maximum of 0.1% tolerance resistors are recommended for desired performance, and the amplifier is internally compensated to operate with optimum gain flatness with RF value of 200 Ω depending on PCB layout, and load resistance.

The output common mode voltage is set by the VCM pin with a fixed gain of 1V/V. This pin must be driven by a low impedance reference and must be bypassed to ground with a 0.1-µF ceramic capacitor. Any unwanted signal coupling into the VCM pin is passed along to the outputs, reducing the performance of the amplifier.

The LMH6554 can be configured to operate on a single 5V supply connected to V+ with V- grounded or configured for a split supply operation with V+ = +2.5V and V− = −2.5V. Operation on a single 5V supply, depending on gain, is limited by the input common mode range; therefore, AC coupling can be required. Split supplies allows much less restricted AC and DC coupled operation with optimum distortion performance.