SBASAB5 March   2024 ADC3683-SP

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics - Power Consumption
    6. 5.6 Electrical Characteristics - DC Specifications
    7. 5.7 Electrical Characteristics - AC Specifications
    8. 5.8 Timing Requirements
    9. 5.9 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Analog Input
        1. 7.3.1.1 Analog Front End Design
          1. 7.3.1.1.1 Sampling Glitch Filter Design
          2. 7.3.1.1.2 Analog Input Termination and DC Bias
            1. 7.3.1.1.2.1 AC-Coupling
            2. 7.3.1.1.2.2 DC-Coupling
        2. 7.3.1.2 Auto-Zero Feature
      2. 7.3.2 Clock Input
        1. 7.3.2.1 Single Ended vs Differential Clock Input
        2. 7.3.2.2 Signal Acquisition Time Adjust
      3. 7.3.3 Voltage Reference
        1. 7.3.3.1 Internal Voltage Reference
        2. 7.3.3.2 External Voltage Reference (VREF)
        3. 7.3.3.3 External Voltage Reference with Internal Buffer (REFBUF)
      4. 7.3.4 Digital Down Converter
        1. 7.3.4.1 DDC MUX
        2. 7.3.4.2 Digital Filter Operation
        3. 7.3.4.3 FS/4 Mixing with Real Output
        4. 7.3.4.4 Numerically Controlled Oscillator (NCO) and Digital Mixer
        5. 7.3.4.5 Decimation Filter
        6. 7.3.4.6 SYNC
        7. 7.3.4.7 Output Formatting with Decimation
      5. 7.3.5 Digital Interface
        1. 7.3.5.1 Output Formatter
        2. 7.3.5.2 Output Scrambler
        3. 7.3.5.3 Output Bit Mapper
          1. 7.3.5.3.1 2-Wire Mode
          2. 7.3.5.3.2 1-Wire Mode
          3. 7.3.5.3.3 ½-Wire Mode
        4. 7.3.5.4 Output Interface or Mode Configuration
          1. 7.3.5.4.1 Configuration Example
        5. 7.3.5.5 Output Data Format
      6. 7.3.6 Test Pattern
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Power Down Options
      3. 7.4.3 Digital Channel Averaging
    5. 7.5 Programming
      1. 7.5.1 Configuration using PINs only
      2. 7.5.2 Configuration using the SPI interface
        1. 7.5.2.1 Register Write
        2. 7.5.2.2 Register Read
  9. 8 Application Information Disclaimer
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Signal Path
        2. 8.2.2.2 Sampling Clock
        3. 8.2.2.3 Voltage Reference
      3. 8.2.3 Application Curves
    3. 8.3 Initialization Set Up
      1. 8.3.1 Register Initialization During Operation
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  10. 9 Register Map
    1. 9.1 Detailed Register Description
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Mechanical Data

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • HBP|64
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.4.2 Digital Filter Operation

The complex decimation operation is illustrated with an example in Figure 7-19. First, the input signal (and the negative image) are frequency shifted by the NCO frequency as shown on the left side of the image. Next, a digital filter is applied (centered around 0 Hz) and the output data rate is decimated by 8 complex, In this example, the output data rate FS,OUT = FS/8 with a Nyquist zone of FS/16. During the complex mixing, the spectrum (signal and noise) is split into real and complex parts, so the amplitude is reduced by 6dB. To compensate this loss, there is a 6dB digital gain option in the decimation filter block that can be enabled via SPI write.

GUID-8697A01F-E667-4EDC-B2CD-39D0C8282F82-low.gifFigure 7-19 Complex decimation illustration

The real decimation operation is shown in Figure 7-20. There is no frequency shift happening, and only the real portion of the complex digital filter is exercised. The output data rate is decimated . A decimation of 8 results in an output data rate FS,OUT = FS/8 with a Nyquist zone of FS/16.

During the real mixing, the spectrum (signal and noise) amplitude is reduced by 3dB. To compensate this loss, there is a 3dB digital gain option in the decimation filter block that can be enabled via SPI write.

GUID-D05EA79B-CAD4-4E52-97EB-16088172D1B2-low.gifFigure 7-20 Real decimation illustration