SBASAU8 December   2024 ADC3649

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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 - Power Consumption
    6. 6.6  Electrical Characteristics - DC Specifications
    7. 6.7  Electrical Characteristics - AC Specifications (ADC3648 - 250 MSPS)
    8. 6.8  Electrical Characteristics - AC Specifications (ADC3649 - 500 MSPS)
    9. 6.9  Timing Requirements
    10. 6.10 Typical Characteristics, ADC3648
    11. 6.11 Typical Characteristics, ADC3649
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Inputs
        1. 8.3.1.1 Nyquist Zone Selection
        2. 8.3.1.2 Analog Front End Design
      2. 8.3.2 Sampling Clock
      3. 8.3.3 Multi-Chip Synchronization
        1. 8.3.3.1 SYSREF Monitor
      4. 8.3.4 Time-Stamp
      5. 8.3.5 Overrange
      6. 8.3.6 External Voltage Reference
      7. 8.3.7 Digital Gain
      8. 8.3.8 Decimation Filter
        1. 8.3.8.1 Uncommon Decimation Ratios
        2. 8.3.8.2 Decimation Filter Response
        3. 8.3.8.3 Decimation Filter Configuration
        4. 8.3.8.4 Numerically Controlled Oscillator (NCO)
      9. 8.3.9 Digital Interface
        1. 8.3.9.1 Parallel LVDS
        2. 8.3.9.2 Serial LVDS (SLVDS) with Decimation
          1. 8.3.9.2.1 SLVDS - Status Bit Insertion
        3. 8.3.9.3 Output Data Format
        4. 8.3.9.4 32-bit Output Resolution
        5. 8.3.9.5 Output Scrambler
        6. 8.3.9.6 Output MUX
        7. 8.3.9.7 Test Pattern
    4. 8.4 Device Functional Modes
      1. 8.4.1 Low Latency Mode
      2. 8.4.2 Digital Channel Averaging
      3. 8.4.3 Power Down Mode
    5. 8.5 Programming
      1. 8.5.1 GPIO Programming
      2. 8.5.2 Register Write
      3. 8.5.3 Register Read
      4. 8.5.4 Device Programming
      5. 8.5.5 Register Map
      6. 8.5.6 Detailed Register Description
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Wideband Spectrum Analyzer
      2. 9.2.2 Design Requirements
        1. 9.2.2.1 Input Signal Path
        2. 9.2.2.2 Clocking
      3. 9.2.3 Detailed Design Procedure
        1. 9.2.3.1 Sampling Clock
      4. 9.2.4 Application Performance Plots
    3. 9.3 Initialization Set Up
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.8.1 Uncommon Decimation Ratios

The DDCs can be programmed to have unequal, independent decimation ratios. The output data rate is based on the decimation filter with the lowest decimation ratio. The output samples of the DDCs with higher decimation factors are repeated in the output data stream accordingly. For example if DDC0 is set to /4 and DDC1 to /8, then the output data rate of DDC0 is twice as fast as of DDC1 (Fout0 = FS/4 vs Fout1 = FS/8). Therefore, the output samples of DDC1 are repeated once as illustrated in Figure 8-21.

ADC3649 Unequal Decimation Factors Figure 8-21 Unequal Decimation Factors