JAJSEU5D October   2014  – February 2018 LMH5401

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
    1.     歪みと周波数との関係(G＝12dB、SE-DE、RL＝200rep%#937;、VPP＝2V)
  3. 3 概要
    1.     ADC12J4000を駆動するLMH5401
  4. 4 改訂履歴
  5. 5 Pin Configuration and Functions
    1.     Pin 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
    5. 6.5 Electrical Characteristics: VS = 5 V
    6. 6.6 Electrical Characteristics: VS = 3.3 V
    7. 6.7 Typical Characteristics: 5 V
    8. 6.8 Typical Characteristics: 3.3 V
    9. 6.9 Typical Characteristics: 3.3-V to 5-V Supply Range
  7. 7 Parameter Measurement Information
    1. 7.1  Output Reference Points
    2. 7.2  ATE Testing and DC Measurements
    3. 7.3  Frequency Response
    4. 7.4  S-Parameters
    5. 7.5  Frequency Response with Capacitive Load
    6. 7.6  Distortion
    7. 7.7  Noise Figure
    8. 7.8  Pulse Response, Slew Rate, and Overdrive Recovery
    9. 7.9  Power Down
    10. 7.10 VCM Frequency Response
    11. 7.11 Test Schematics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Fully-Differential Amplifier
        1. 8.3.1.1 Power Down and Ground Pins
      2. 8.3.2 Operations for Single-Ended to Differential Signals
        1. 8.3.2.1 AC-Coupled Signal Path Considerations for Single-Ended Input to Differential Output Conversion
        2. 8.3.2.2 DC-Coupled Input Signal Path Considerations for SE-DE Conversions
        3. 8.3.2.3 Resistor Design Equations for Single-to-Differential Applications
        4. 8.3.2.4 Input Impedance Calculations
      3. 8.3.3 Differential-to-Differential Signals
        1. 8.3.3.1 AC-Coupled, Differential-Input to Differential-Output Design Issues
        2. 8.3.3.2 DC-Coupled, Differential-Input to Differential-Output Design Issues
      4. 8.3.4 Output Common-Mode Voltage
      5. 8.3.5 LMH5401 Comparison
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation With a Split Supply
      2. 8.4.2 Operation With a Single Supply
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Stability
      2. 9.1.2 Input and Output Headroom Considerations
      3. 9.1.3 Noise Analysis
      4. 9.1.4 Noise Figure
      5. 9.1.5 Thermal Considerations
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Driving Matched Loads
        2. 9.2.2.2 Driving Unmatched Loads For Lower Loss
        3. 9.2.2.3 Driving Capacitive Loads
        4. 9.2.2.4 Driving ADCs
          1. 9.2.2.4.1 SNR Considerations
          2. 9.2.2.4.2 SFDR Considerations
          3. 9.2.2.4.3 ADC Input Common-Mode Voltage Considerations : AC-Coupled Input
          4. 9.2.2.4.4 ADC Input Common-Mode Voltage Considerations : DC-Coupled Input
        5. 9.2.2.5 GSPS ADC Driver
        6. 9.2.2.6 Common-Mode Voltage Correction
        7. 9.2.2.7 Active Balun
      3. 9.2.3 Application Curves
    3. 9.3 Do's and Don'ts
      1. 9.3.1 Do:
      2. 9.3.2 Don't:
  10. 10Power Supply Recommendations
    1. 10.1 Supply Voltage
    2. 10.2 Single-Supply
    3. 10.3 Split-Supply
    4. 10.4 Supply Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 デバイス・サポート
      1. 12.1.1 デバイスの項目表記
    2. 12.2 ドキュメントのサポート
      1. 12.2.1 関連資料
    3. 12.3 ドキュメントの更新通知を受け取る方法
    4. 12.4 コミュニティ・リソース
    5. 12.5 商標
    6. 12.6 静電気放電に関する注意事項
    7. 12.7 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9.1.4 Noise Figure

Noise figure (NF) is a helpful measurement in an RF system design. The basis of this calculation is to define how much thermal noise the system (or even on the component) adds to this input signal. All systems are assumed to have a starting thermal noise power of –174 dBm/√Hz at room temperature calculated from P(dBW) = 10 × log (kTB), where T is temperature in Kelvin (290k), B is bandwidth in Hertz (1 Hz), and k is Boltzmann's constant 1.38 × 10–23 (J / K). Whenever an element is placed in a system, additional noise is added beyond the thermal noise floor. The noise factor (NF) helps calculate the noise figure and is the ratio between the input SNR and the output SNR. Input SNR includes the noise contribution from the resistive part of the source impedance, ZS. NF is relative to the source impedance used in the measurement or calculation because capacitors and inductors are known to be noiseless. Equation 9 calculates NF:

Equation 9. NF = 10 log (eno2 / enZs)

where

  • en(Zs) is the thermal noise of the source resistance and equal to 4 kTRS (GDT)2,
  • G is the voltage gain of the amplifier.

From Equation 10, NF is approximately equal to 10 dB which is the just above the actual value of 9.6 dB measured on the bench at 200 MHz when referenced to 50 Ω and as shown in Figure 59.

Equation 10. LMH5401 q_dt_sbos710.gif

For thermal noise calculations with different source resistances, Equation 11 can be used to calculate the NF change with a new source resistance. For example, Equation 9 uses a source resistance of 50 Ω. By using a source of 100 Ω, the new noise figure calculation (Equation 11) yields an NF of 6.6 dB, which provides a 3-dB improvement that results from the increase in Zs.

Equation 11. en(Zs) = kTRs