SLASE16B January   2014  – May 2014 DAC37J82 , DAC38J82

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  Handling Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  DC Electrical Characteristics
    6. 6.6  Digital Electrical Characteristics
    7. 6.7  AC Electrical Characteristics
    8. 6.8  Timing Requirements
    9. 6.9  Switching Characteristics
    10. 6.10 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  Serdes Input
      2. 7.3.2  Serdes Rate
      3. 7.3.3  Serdes PLL
      4. 7.3.4  Serdes Equalizer
      5. 7.3.5  JESD204B Descrambler
      6. 7.3.6  JESD204B Frame Assembly
      7. 7.3.7  Serial Peripheral Interface (SPI)
      8. 7.3.8  Multi-Device Synchronization
      9. 7.3.9  Input Multiplexer
      10. 7.3.10 FIR Filters
      11. 7.3.11 Full Complex Mixer
      12. 7.3.12 Coarse Mixer
      13. 7.3.13 Dithering
      14. 7.3.14 Complex Summation
      15. 7.3.15 Quadrature Modulation Correction (QMC)
        1. 7.3.15.1 Gain and Phase Correction
        2. 7.3.15.2 Offset Correction
      16. 7.3.16 Group Delay Correction Block
        1. 7.3.16.1 Fine Fractional Delay FIR Filter
        2. 7.3.16.2 Coarse Fractional Delay FIR Filter
      17. 7.3.17 Output Multiplexer
      18. 7.3.18 Power Measurement And Power Amplifier Protection
      19. 7.3.19 Serdes Test Modes
      20. 7.3.20 Error Counter
      21. 7.3.21 Eye Scan
      22. 7.3.22 JESD204B Pattern Test
      23. 7.3.23 Temperature Sensor
      24. 7.3.24 Alarm Monitoring
      25. 7.3.25 LVPECL Inputs
      26. 7.3.26 CMOS Digital Inputs
      27. 7.3.27 Reference Operation
      28. 7.3.28 Analog Outputs
      29. 7.3.29 DAC Transfer Function
    4. 7.4 Device Functional Modes
      1. 7.4.1 Clocking Modes
        1. 7.4.1.1 PLL Bypass Mode
        2. 7.4.1.2 PLL Mode
      2. 7.4.2 PRBS Test Mode
    5. 7.5 Register Map
      1. 7.5.1 Register Descriptions
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Low-IF Wideband LTE Transmitter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Data Input Rate
          2. 8.2.1.2.2 Intermediate Frequency
          3. 8.2.1.2.3 Interpolation
          4. 8.2.1.2.4 DAC PLL Setup
          5. 8.2.1.2.5 Serdes Lanes
        3. 8.2.1.3 Application Performance Plots
      2. 8.2.2 Zero-IF Wideband Transmitter
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Data Input Rate
          2. 8.2.2.2.2 Interpolation
          3. 8.2.2.2.3 Serdes Lanes
          4. 8.2.2.2.4 LO Feedthrough and Sideband Correction
        3. 8.2.2.3 Application Performance Plots
    3. 8.3 Initialization Set Up
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Related Links
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

10 Layout

10.1 Layout Guidelines

  • DAC output termination resistors should be placed as close to the output pins as possible to provide a DC path to ground and set the source impedance.
  • For PLL mode, if the external loop filter is not used then leave the pin floating without any board routing. Signals coupling to this node may cause clock mixing spurs in the DAC output.
  • Route the high speed serdes lanes as impedance-controlled, tightly-coupled, differential traces.
  • Maintain a solid ground plane under the serdes lanes without any ground plane splits.
  • AC couple the serdes lines between the logic device and the DAC using 0201 size capacitors that maintain low impedance at the serialized data rate.
  • Simulation of the serdes channel is recommended to verify JESD204B standard compliance to ensure compatibility between devices.
  • Keep the SYSREF routing away from the DACCLK routing to reduce coupling. Using a pulsed SYSREF or disabling a continuous SYSREF is recommended during normal operation to avoid spurs in the output spectrum.
  • Keep routing for RBIAS short, for instance a resistor can be placed on the bottom of the board directly connecting the RBIAS ball to a GND ball.
  • Decoupling capacitors should be placed as close to the supply pins as possible, for instance a capacitor can be placed on the bottom of the board directly connecting the supply ball to a GND ball.
  • Noisy power supplies should be routed away from clean supplies. Use two power plane layers, preferably with a GND layer in between.

10.2 Layout Examples

Power_lase16.gifFigure 87. DAC37J82/DAC38J82 Layout for Power Supplies
Signal_lase17.gifFigure 88. DAC37J82/DAC38J82 Layout for Signals