SBOS877A April   2018  – September 2018 THS6301

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      MTPR G.Fast 212 MHz (Bias 10, PAR = 15 dB, 1-in-64 Missing Tones)
      2.      Multitone Power Ratio (MTPR) Profile (G.Fast, 212 MHz, 8 dBm)
  4. 4 Revision History
  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
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
  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 Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Dissipation and Thermal Considerations
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2 Detailed Design Procedure

The G.Fast signal input to the THS6301 comes from a high-speed DAC whose interleaving spurs are filtered out using either a 3rd- or 5th-order filter. Digital pre-emphasis can be employed in the DAC output such that the differential line driver compensates for the transmission line cable losses at long distance and high frequency. The THS6301 is operated on a 12-V single supply. Resulting from the single-supply operation, the device input is AC-coupled using a capacitor that blocks any DC current flowing out of the inputs to the adjacent circuitry. The AC-coupling capacitor forms a high-pass filter with the device input impedance. This pole must be set at a frequency low enough to not interfere with the desired xDSL or G.Fast signal.

The THS6301 differential outputs usually drive a 1:n output transformer with a transformer turns ratio that can be changed depending upon the application. The output transformer selected must have low insertion loss in the desired frequency band in order to maintain good multi-tone power rejection (MTPR) for a given line power. The load is expected to be a transmission line with 100-Ω characteristic impedance on the primary side of the transformer. Referred to the transformer secondary, the load detected by the amplifier is 1 / n2 with 1:n being the transformer turn ratio. Practical limitations force the transformer-turn ratio to be between 1:1 and 1:1.6. At the lighter load detected by the amplifier (1:1), the voltage swing is limited by the class AB output stage and the maximum achievable swing of the amplifier. At the heaviest load (1:1.6), the voltage swing is limited by the current drive capability of the amplifier. To satisfy the synthesis impedance factor and the loading, the termination resistance (RT) can be set to RT = RL / 5 = 100 Ω / (5 × n2).

For surge protection, consider adding a gas discharge tube (GDT) on the primary side of the output transformer. The gas discharge tube is required to shunt the large current that could flow through the cables during lightning surge, and protect the device outputs. The secondary protection is also normally added after the series resistance on the secondary transformer side. The secondary protection could be in the form of back to back switching diodes, which also help limit the residual surge current flowing into the device outputs.

For the power-supply bypass, consider using X7R or X5R because of the better stability of these materials over temperature.