SBOS695A August   2014  – December 2014 LMH3401


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: VS = 5 V
    6. 7.6 Electrical Characteristics: VS = 3.3 V
    7. 7.7 Typical Characteristics
  8. Parameter Measurement Information
    1. 8.1  Output Reference Points
    2. 8.2  ATE Testing and DC Measurements
    3. 8.3  Frequency Response
    4. 8.4  S-Parameters
    5. 8.5  Frequency Response with Capacitive Load
    6. 8.6  Distortion
    7. 8.7  Noise Figure
    8. 8.8  Pulse Response, Slew Rate, Overdrive Recovery
    9. 8.9  Power Down
    10. 8.10 VCM Frequency Response
    11. 8.11 Test Schematics
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Fully-Differential Amplifier
      2. 9.3.2 Single-Ended to Differential Signals
        1. Resistor Design Equations for Single-to-Differential Applications
        2. Input Impedance Calculations
      3. 9.3.3 Differential to Differential Signals
      4. 9.3.4 Output Common-Mode Voltage
    4. 9.4 Device Functional Modes
      1. 9.4.1 Operation with a Split Supply
      2. 9.4.2 Operation with a Single Supply
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Input and Output Headroom Considerations
      2. 10.1.2 Noise Analysis
      3. 10.1.3 Thermal Considerations
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. Driving Matched Loads
        2. Driving Capacitive Loads
        3. Driving ADCs
          1. SNR Considerations
          2. SFDR Considerations
          3. ADC Input Common-Mode Voltage Considerations—AC-Coupled Input
          4. ADC Input Common-Mode Voltage Considerations—DC-Coupled Input
        4. GSPS ADC Driver
        5. Common-Mode Voltage Correction
        6. Active Balun
        7. Application Curves
    3. 10.3 Do's and Don'ts
      1. 10.3.1 Do:
      2. 10.3.2 Don't:
  11. 11Power-Supply Recommendations
    1. 11.1 Supply Voltage
    2. 11.2 Single Supply
    3. 11.3 Split Supply
    4. 11.4 Supply Decoupling
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Device Nomenclature
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

11 Power-Supply Recommendations

The LMH3401 can be used with either split or single-ended power supplies. The ideal supply voltage is a 5.0-V total supply, split around the desired common-mode of the output signal swing. For example, if the LMH3401 is used to drive an ADC with a 1.0-V input common mode, then the ideal supply voltages are 3.5 V and –1.5 V. The GND pin can then be connected to the system ground and the PD pin is ground referenced.

11.1 Supply Voltage

Using a 5-V power supply gives the best balance of performance and power dissipation. If power dissipation is a critical design criteria a power supply as low as 3.3 V (±1.65) can be used. When using a lower power supply, the input common-mode and output swing capabilities are drastically reduced. Make sure to study the common-mode voltages required before deciding on a lower-voltage power supply. In most cases the extra performance achieved with 5-V supplies is worth the power.

11.2 Single Supply

Single-supply voltages from 3.3 V to 5 V are supported. When using a single supply check both the input and output common-mode voltages that are required by the system.

11.3 Split Supply

In general, split supplies allow the most flexibility in system design. To operate as split supply, apply the positive supply voltage to VS+, the negative supply voltage to VS–, and the ground reference to GND. Note that supply voltages do not need to be symmetrical. Provided the total supply voltage is between 3.3 V and 5.25 V, any combination of positive and negative supply voltages is acceptable. This feature is often used when the output common-mode voltage must be set to a particular value. For best performance, the power-supply voltages are symmetrical around the desired output common-mode voltage. The input common-mode voltage range is much more flexible than the output.

11.4 Supply Decoupling

Power-supply decoupling is critical to high-frequency performance. Onboard bypass capacitors are used on the LMH3401EVM; however, the most important component of the supply bypassing is provided by the PCB. As illustrated in Figure 71, there are multiple vias connecting the LMH3401 power planes to the power-supply traces. These vias connect the internal power planes to the LMH3401. Both VS+ and VS– must be connected to the internal power planes with several square centimeters of continuous plane in the immediate vicinity of the amplifier. The capacitance between these power planes provides the bulk of the high-frequency bypassing for the LMH3401.