SLOS738E September   2012  – August 2015 AFE5809

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 Demodulator Electrical Characteristics
    7. 7.7  Digital Characteristics
    8. 7.8  Switching Characteristics
    9. 7.9  SPI Switching Characteristics
    10. 7.10 Output Interface Timing Requirements (14-bit)
    11. 7.11 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 LNA
      2. 8.3.2 Voltage-Controlled Attenuator
      3. 8.3.3 PGA
      4. 8.3.4 ADC
      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 Digital I/Q Demodulator
      7. 8.3.7 Equivalent Circuits
      8. 8.3.8 LVDS Output Interface Description
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Serial Peripheral Interface (SPI) Operation
        1. 8.5.1.1 ADC/VCA Serial Register Write Description
        2. 8.5.1.2 ADC/VCA Serial Register Readout Description
        3. 8.5.1.3 Digital Demodulator SPI Description
    6. 8.6 Register Maps
      1. 8.6.1 ADC and VCA Register Description
        1. 8.6.1.1 ADC Register Map
        2. 8.6.1.2 AFE5809 ADC Register/Digital Processing Description
          1. 8.6.1.2.1  AVERAGING_ENABLE: Address: 2[11]
          2. 8.6.1.2.2  ADC_OUTPUT_FORMAT: Address: 4[3]
          3. 8.6.1.2.3  ADC Reference Mode: Address 1[13] and 3[15]
          4. 8.6.1.2.4  DIGITAL_GAIN_ENABLE: Address: 3[12]
          5. 8.6.1.2.5  DIGITAL_HPF_ENABLE
          6. 8.6.1.2.6  DIGITAL_HPF_FILTER_K_CHX
          7. 8.6.1.2.7  LOW_FREQUENCY_NOISE_SUPPRESSION: Address: 1[11]
          8. 8.6.1.2.8  LVDS_OUTPUT_RATE_2X: Address: 1[14]
          9. 8.6.1.2.9  CHANNEL_OFFSET_SUBSTRACTION_ENABLE: Address: 3[8]
          10. 8.6.1.2.10 SERIALIZED_DATA_RATE: Address: 3[14:13]
          11. 8.6.1.2.11 TEST_PATTERN_MODES: Address: 2[15:13]
          12. 8.6.1.2.12 SYNC_PATTERN: Address: 10[8]
        3. 8.6.1.3 VCA Register Map
        4. 8.6.1.4 VCA Register Description
          1. 8.6.1.4.1 LNA Input Impedances Configuration (Active Termination Programmability)
          2. 8.6.1.4.2 Programmable Gain for CW Summing Amplifier
          3. 8.6.1.4.3 Programmable Phase Delay for CW Mixer
      2. 8.6.2 Digital Demodulator Register Description
        1. 8.6.2.1 Profile RAM and Coefficient RAM
          1. 8.6.2.1.1 Programming the Profile RAM
          2. 8.6.2.1.2 Procedure for Configuring Next Profile Vector
          3. 8.6.2.1.3 Programming the Coefficient RAM
          4. 8.6.2.1.4 Filter Coefficent Test Mode
          5. 8.6.2.1.5 TX_SYNC and SYNC_WORD Timing
          6. 8.6.2.1.6 FIR Filter Delay versus TX_TRIG Timing
  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 Low Frequency Support
        5. 9.2.2.5 ADC Operation
          1. 9.2.2.5.1 ADC Clock Configurations
          2. 9.2.2.5.2 ADC Reference Circuit
      3. 9.2.3 Application Curves
    3. 9.3 System Example
      1. 9.3.1 ADC Debug
      2. 9.3.2 VCA Debug
    4. 9.4 Do's and Don'ts
      1. 9.4.1 Driving the Inputs (Analog or Digital) Beyond the Power-Supply Rails
      2. 9.4.2 Driving the Device Signal Input With an Excessively High Level Signal
      3. 9.4.3 Driving the VCNTL Signal With an Excessive Noise Source
      4. 9.4.4 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. 9.4.5 LVDS Routing Length Mismatch
      6. 9.4.6 Failure to Provide Adequate Heat Removal
  10. 10Power Supply Recommendations
    1. 10.1 Power/Performance Optimization
    2. 10.2 Power Management Priority
    3. 10.3 Partial Power-Up and Power-Down Mode
    4. 10.4 Complete Power-Down Mode
    5. 10.5 Power Saving in CW Mode
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

5 Description (continued)

The AFE5809 device contains eight channels of voltage controlled amplifier (VCA), 14, and 12-bit ADC, and CW mixer. The VCA includes LNA, VCAT, PGA, and LPF. The LNA gain is programmable to support 250 mVPP to 1 VPP input signals. Programmable active termination is also supported by the LNA. The ultra-low noise VCAT provides an attenuation control range of 40 dB and improves overall low-gain SNR, which benefits harmonic imaging and near-field imaging. The PGA provides gain options of 24 and 30 dB. Before the ADC, a LPF can be configured as 10, 15, 20, or 30 MHz to support ultrasound applications with different frequencies. In addition, the signal chain of the AFE5809 device can handle signal frequency lower than 100 kHz, which enables the device to be used in both sonar and medical applications. The high-performance 14-bit/65-MSPS ADC in the AFE5809 device achieves 77-dBFS SNR. It ensures excellent SNR at low chain gain. The ADC’s LVDS outputs enable flexible system integration desired for miniaturized systems.

The AFE5809 device integrates a low-power passive mixer and a low-noise summing amplifier to accomplish on-chip CWD beamformer. 16 selectable phase-delays can be applied to each analog input signal. Meanwhile, a unique third- and fifth-order harmonic suppression filter is implemented to enhance CW sensitivity.

The AFE5809 device also includes a digital in-phase and quadrature (I/Q) demodulator and a low-pass decimation filter. The main purpose of the demodulation block is to reduce the LVDS data rate and improve overall system power efficiency. The I/Q demodulator can accept ADC output with up to 65 MSPS sampling rate and 14-bit resolution. For example, after digital demodulation and 4× decimation filtering, the data rate for either in-phase or quadrature output is reduced to 16.25 MSPS and the data resolution is improved to 16 bits, consequently. Hence, the overall LVDS trace reduction can be a factor of 2. This demodulator can be bypassed and powered down completely if it is not needed.

The AFE5809 device is available in a 15-mm × 9-mm, 135-pin BGA package, and it is specified for operation from 0°C to 85°C.

NOTE

AFE5809 with date code later than 2014, that is date code >41XXXX, has below additional features which can be enabled by Register 61[15,14,13]. Existing analog performance remains the same.

  • 61[13] enables an additional voltage clamp at the V2I input of the PGA. This limits the amount of overload signal the PGA sees.
  • 61[14] enables a first-order 5-MHz LPF filter to suppress signals >5 MHz or high-order harmonics.
  • 61[15] enables a –6-dB PGA clamp setting. The actual PGA output is less than the ADC's full-scale amplitude, 2 Vpp.