SLOS729D October   2011  – November 2015 AFE5808A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 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
    6. 7.6  Digital Characteristics
    7. 7.7  Switching Characteristics
    8. 7.8  Timing Requirements
    9. 7.9  Output Interface Timing
    10. 7.10 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Low-Noise Amplifier (LNA)
      2. 8.3.2 Voltage-Controlled Attenuator
      3. 8.3.3 Programmable Gain Amplifier
      4. 8.3.4 Analog-to-Digital Converter
      5. 8.3.5 Continuous-Wave (CW) Beamformer
        1. 8.3.5.1 16 × ƒcw Mode
        2. 8.3.5.2 8 × ƒcw and 4 × ƒcw Modes
        3. 8.3.5.3 1 × ƒcw Mode
      6. 8.3.6 Equivalent Circuits
      7. 8.3.7 LVDS Output Interface Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 TGC Mode
      2. 8.4.2 CW Mode
      3. 8.4.3 TGC + CW Mode
      4. 8.4.4 Test Modes
        1. 8.4.4.1 ADC Test Modes
        2. 8.4.4.2 VCA Test Mode
      5. 8.4.5 Power Management
        1. 8.4.5.1 Power and Performance Optimization
        2. 8.4.5.2 Power Management Priority
        3. 8.4.5.3 Partial Power Up and Power Down Mode
        4. 8.4.5.4 Complete Power-Down Mode
        5. 8.4.5.5 Power Saving in CW Mode
    5. 8.5 Programming
      1. 8.5.1 Serial Register Timing
        1. 8.5.1.1 Serial Register Write Description
        2. 8.5.1.2 Register Readout Description
    6. 8.6 Register Maps
      1. 8.6.1 ADC Register Map
      2. 8.6.2 ADC Register/Digital Processing Description
        1. 8.6.2.1  AVERAGING_ENABLE: Address: 2[11]
        2. 8.6.2.2  ADC_OUTPUT_FORMAT: Address: 4[3]
        3. 8.6.2.3  DIGITAL_GAIN_ENABLE: Address: 3[12]
        4. 8.6.2.4  DIGITAL_HPF_ENABLE
        5. 8.6.2.5  DIGITAL_HPF_FILTER_K_CHX
        6. 8.6.2.6  LOW_FREQUENCY_NOISE_SUPPRESSION: Address: 1[11]
        7. 8.6.2.7  LVDS_OUTPUT_RATE_2X: Address: 1[14]
        8. 8.6.2.8  CHANNEL_OFFSET_SUBSTRACTION_ENABLE: Address: 3[8]
        9. 8.6.2.9  SERIALIZED_DATA_RATE: Address: 3[14:13]
        10. 8.6.2.10 TEST_PATTERN_MODES: Address: 2[15:13]
        11. 8.6.2.11 SYNC_PATTERN: Address: 10[8]
      3. 8.6.3 VCA Register Map
      4. 8.6.4 AFE5808A VCA Register Description
        1. 8.6.4.1 LNA Input Impedances Configuration (Active Termination Programmability)
        2. 8.6.4.2 Programmable Gain for CW Summing Amplifier
        3. 8.6.4.3 Programmable Phase Delay for CW Mixer
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 LNA Configuration
          1. 9.2.2.1.1 LNA Input Coupling and Decoupling
          2. 9.2.2.1.2 LNA Noise Contribution
          3. 9.2.2.1.3 Active Termination
          4. 9.2.2.1.4 LNA Gain Switch Response
        2. 9.2.2.2 Voltage-Controlled-Attenuator
        3. 9.2.2.3 CW Operation
          1. 9.2.2.3.1 CW Summing Amplifier
          2. 9.2.2.3.2 CW Clock Selection
          3. 9.2.2.3.3 CW Supporting Circuits
        4. 9.2.2.4 ADC Operation
          1. 9.2.2.4.1 ADC Clock Configurations
          2. 9.2.2.4.2 ADC Reference Circuit
      3. 9.2.3 Application Curves
    3. 9.3 Do's and Don'ts
      1. 9.3.1 Driving the Inputs (Analog or Digital) Beyond the Power-Supply Rails
      2. 9.3.2 Driving the Device Signal Input With an Excessively High Level Signal
      3. 9.3.3 Driving the VCNTL Signal With an Excessive Noise Source
      4. 9.3.4 Using a Clock Source With Excessive Jitter, an Excessively Long Input Clock Signal Trace, or Having Other Signals Coupled to the ADC or CW Clock Signal Trace
      5. 9.3.5 LVDS Routing Length Mismatch
      6. 9.3.6 Failure to Provide Adequate Heat Removal
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Documentation
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

11 Layout

11.1 Layout Guidelines

Proper grounding and bypassing, short lead length, and the use of ground and power-supply planes are particularly important for high-frequency designs. Achieving optimum performance with a high-performance device such as the AFE5808A requires careful attention to the PCB layout to minimize the effects of board parasitics and optimize component placement. A multilayer PCB usually ensures best results and allows convenient component placement. To maintain proper LVDS timing, all LVDS traces should follow a controlled impedance design. In addition, all LVDS trace lengths should be equal and symmetrical; TI recommends to keep trace length variations less than 150 mil (0.150 inch or 3.81 mm).

NOTE

To avoid noise coupling through supply pins, TI recommends to keep sensitive input pins, such as INM, INP, ACT pins aways from the AVDD 3.3 V and AVDD_5V planes. For example, either the traces or vias connected to these pins should NOT be routed across the AVDD 3.3 V and AVDD_5V planes, that is to avoid power planes under INM, INP, and ACT pins.

In addition, appropriate delay matching should be considered for the CW clock path, especially in systems with high channel count. For example, if clock delay is half of the 16x clock period, a phase error of 22.5°C could exist. Thus the timing delay difference among channels contributes to the beamformer accuracy.

Additional details on BGA PCB layout techniques can be found in the Texas Instruments Application Report, MicroStar BGA Packaging Reference Guide (SSYZ015), which can be downloaded from www.ti.com.

11.2 Layout Example

AFE5808A Laye1.gif Figure 94. Layout Example: I/O Routing
AFE5808A Layer2.gif Figure 95. Layout Example: Power Plane
AFE5808A Layer3.gif Figure 96. Layout Example: Power Plane
AFE5808A Layer4.gif Figure 97. Layout Example: LVDS and CLK I/Os